RAC1 and microcephaly: Other genes within the combined network are involved in neuronal progenitor cell proliferation, a common mechanism underlying microcephaly[47](RAC1[48,49] and GNB1[50]) and neuronal development (CEBPB[51], L1CAM[52], MAPT[53], PAK2[54], SPTBN1[55], and YWHAE[56,57]).