RT-PCR analysis of genes reported to be specific to mouse ES cells. (A) RT-PCR analysis of Dppa5, Dax-1, Zf296, and DNMT3L genes. (B) RT-PCR analysis of FBX15 and HRASP (ERAS) genes. FBX15 and HRASP were not detected in any cell line, whereas DNMT3L was present though levels were variable.