We compared cMaf, MafB and Cxcr7 RNA expression at E12.5 and E15.5 and identified some important features (Figures 7, S2A-S2C and S6D-S6F). cMaf, MafB and Cxcr7 RNAs were expressed in the SVZ of the dorsal MGE (and not the ventral MGE), and were maintained in cells migrating through the LGE and CGE and then into the cortex at E12.5 and E15.5 (Figure 7, S2A-S2C and S6D-S6F). cMaf, MafB and CXCR7 appear to be excellent markers of the cortical interneuron lineage, as we did not detect their expression in other MGE-derived structures, such as the ventral pallidum or globus pallidus at E12.5, E15.5 or P0 (Figures 7, S2A-S2C, S6D-S6F and data not shown). In the E15.5 and P0 striatum, these genes showed little expression (Figure 7), except for MafB and cMaf in a very small population of cells (data not shown). Thus, unlike other cortical interneuron markers that are also expressed in striatal interneurons (e.g. Dlx1, Lhx6, parvalbumin, Sst), cMaf, MafB and CXCR7 expression largely mark only cortical interneurons.
