A, RT-qPCR quantification of spinal cord mRNA levels of Sox2, Sox10, Pdgfrα, Plp-E3b (exon3b-containing proteolipid protein), Cnp, Qk (also known as CC1), and premyelinating OL-specific Enpp6 at P19. Gene expression was normalized to the internal control Hsp90, and the level in non-Cre Ctrl was set to 1. N = 7 non-Cre control (black circles) and 4 Sox2 cKO (red triangles), two-tailed Student’s t test [t(9) = 5.397 Sox2, t(9) = 3.131 Sox10, t(9) = 2.437 Pdgfrα, t(9) = 11.71 Plp-E3b, t(9) = 5.145 Cnp, t(9) = 4.487 Qk, and t(9) = 2.734 Enpp6]. B, Western blotting of myelin proteins MBP and CNP, and the loading control β-actin in the P19 spinal cord.