Cortical Layer Markers
Learn about the development of cortical layers, and explore the specific markers for each layer to use in your IHC, ICC-IF, or Western blot assays.
Cortical layer markers are useful tools for studying the cerebral cortex's development, functional neuroanatomy, and pathology. The cerebral cortex is organized into six layers of both morphologically and functionally divergent neurons. The different layers can be identified using antibodies against protein markers expressed in specific layers.
Development and characteristics of cortical layers
Cortical layers are formed during embryonal development.
The neuronal layers in the cortex generate in a strictly regulated manner during embryonal development. Specifically, layers V and VI, the deeper layers, develop after the formation of the cortical plate. Layers II-IV, the upper layers neurons, are formed after the deeper layers. Glial cells, including astrocytes and oligodendrocytes, generate at the latest stages of cortical development.

Neocortical neurogenesis is dependent on several transcriptional factors. For instance, LHX2 and PAX6 together play a crucial role in the specification of neocortical progenitors, giving rise to the projection neurons. MEF2C is another example of a transcription factor essential for normal neural development and spatial distribution in the neocortex.
Anatomical and functional diversity in neurons of different layers
Neurons of different layers are anatomically and functionally diverse in the mature neocortex. Neuronal cell morphology, physiological properties, and anatomical connections vary between the layers. Neurons of layers II/III, along with a subset of neurons of layer V, contribute primarily to intracortical connections, including callosal projections to the contralateral cerebral hemisphere. Layer V corticofugal neurons target the midbrain, hindbrain, and spinal cord, while layer VI neurons project mainly to the thalamus.

The cortical layer markers CUX1, POUF3F2, BCL11B, and FOXP2
Protein expression profiles differ in neurons of various layers. For instance, upper layers neurons can be identified by expression of CUX1 and POU3F2 (BRN2), the neurons of layer V by expression of BCL11B (CTIP2), and layer VI can be identified by FOXP2 expression.

Antibodies targeting cortical layer I

Layer 1: Anti-RELN monoclonal antibody (AMAb91365)
- Validated for ICC-IF
- Verified species reactivity: human

Layer 1: Anti-RELN polyclonal antibody (HPA046512)
- Validated for ICC-IF
- Verified species reactivity: human
Antibodies targeting upper cortical layers
Antibodies targeting proteins in the cortical layers II-IV, include CUX1 (CUTL1) and POU3F2 (BRN2).

Layer 2/3: Anti-RASGRF2 polyclonal antibody (HPA018679)
- Validatd for IHC
- Verified species reactivity: human, rat

Layer 2/3: Anti-CALB1 polyclonal antibody (HPA023099)
- Validated for IHC, WB, ICC-IF
- Verified species reactivitity: human

Layer 2/3-4: Anti-CUX1 monoclonal antibody (AMAb91352)
- Validated for IHC, ICC-IF
- Verified species reactivity: human

Layer 2/3-4: Anti-CUX1 monoclonal antibody (AMAb91353)
- Validated for: IHC, ICC-IF
- Verified species reactivity: human

Layer 2/3-4: Anti-CUX1 polyclonal antibody (HPA003277)
- Validated for IHC
- Verified species reactivity: human, mouse, rat

Layer 2/3, 4 and 5b: Anti-POU3F2 (BRN2) polyclonal antibody (HPA056261)
- Validated for ICC-IF
- Verified species reactivity: human, mouse, rat

Layer 2/3, 4 and 5b: Anti-POU3F2 (BRN2) monoclonal antibody (AMAb91406)
- Validated for IHC, WB, ICC-IF
- Verified species reacitivity: mouse

Layer 2/3, 4 and 5b: Anti-POU3F2 (BRN2) monoclonal antibody (AMAb91407)
- Validated for IHC, ICC-IF
- Verified species reactivity: mouse, rat

Layer 2-4 (mainly 4): Anti-NECAB1 monoclonal antibody (AMAb90798)
- Validated for IHC, WB
- Verified species reactivity: human

Layer 2-4 (mainly 4): Anti-NECAB1 monoclonal antibody (AMAb90800)
- Validated for IHC, WB
- Verified species reactivity: human

Layer 2-4 (mainly 4): Anti-NECAB1 monoclonal antibody (AMAb90801)
- Validated for IHC, WB
- Verified species reactivity: human, mouse, rat

Layer 2-4 (mainly 4): Anti-NECAB1 polyclonal antibody (HPA023629)
- Validated for IHC, WB
- Verified species reactivity: human, mouse, rat

Layer 2-4 (mainly 4): Anti-NECAB1 polyclonal antibody (HPA031262)
- Validated for IHC
- Verified species reactivity: human
Antibodies targeting deeper cortical layers V and VI
Antibodies targeting layer V and VI include PCP4 and BCL11B (CTIP2).

Layer 5: Anti-PCP4 polyclonal antibody (HPA005792)
- Validated for IHC, WB
- Verified species reactivity: human, mouse, rat

Layer 5: Anti-CNTC6 polyclonal antibody (HPA016645)
- Validated for IHC
- Verified species reactivity: human

Layer 5-6: Anti-BCL11B (CTIP2) polyclonal antibody (HPA049117)
- Validated for IHC, ICC-IF
- Verified species reactivity: human, mouse, rat

Layer 6: Anti-FOXP2 monoclonal antibody (AMAb91361)
- Validated for IHC, ICC-IF
- Verified species reactivity: human, mouse

Layer 6: Anti-FOXP2 monoclonal antibody (AMAb91362)
- Validated for IHC, ICC-IF
- Verified species reactivity human, mouse, rat

Layer 6: Anti-FOXP2 polyclonal antibody (HPA000382)
- Validated for IHC
- Verified species reactivity: human, mouse, rat

Layer 6: Anti-TLE4 polyclonal antibody (HPA065357)
- Validated for WB, ICC-IF
- Verified species reactivity: mouse, rat

Layer 6b: Anti-CTGF monoclonal antibody (AMAb91366)
- Validated for IHC, WB
- Verified species reactivity: human, mouse, rat

Layer 6b: Anti-CTGF polyclonal antibody (HPA031075)
- Validated for IHC, WB, ICC-IF
- Verified species reactivity: human