(A) ATRA (1 µM) and SAG (10 to 1,000 nM) treatments as well as 1 µM ATRA and 500 ng/µl Shh treatment greatly increased both HB9+ and Is11+ cells. (B) Isl1/βIII-tubulin double-positive cells were observed in ATRA/SAG culture. White bar indicates 20 µm. (C–G) Quantitation of the gene expression levels in ATRA/SAG-treated culture. Two sMN-specific markers, HB9 and Isl1, were upregulated by ATRA/SAG treatment (C, D). A spinal cord marker, HoxB4, was also upregulated (E), while a forebrain marker, BF1, was downregulated by addition of ATRA/SAG (10 and 100 nM) (F). The change in expression of the neural cell marker βIII-tubulin was not statistically significant (G). *p<0.05, **p<0.005 (n = 4).