Relative expression of eight genes in cryopreserved human embryonic stem cells (hESCs). RNA was extracted from hESCs cryopreserved with SCK or a solution of 2 M DMSO, 1 M acetamide, and 3 M DAP. cDNA was then synthesized, and the expression of eight Homo sapiens genes was assessed: GAPDH, SOX2, OCT3/4, KLF4, c-MYC, REX2, ECAD, and EPCAM, determined by RT-PCR. The 2-Ct SCK/2-Ct DAP ratio was calculated for each gene. SOX2 was used as the control gene. Data for the comparative Ct method are shown as mean fold changes ± SD of the expression of each gene. **p < 0.01, *p < 0.05, statistically significant difference versus DAP.