Figure 2: Expression of stem cell marker and pluripotency genes. (A) AP staining of ES/iPS cells cultured on MEF, STO, STO/E, STO/L and STO/EL feeder layers in medium with (MEF+LIF) or without (MEF, STO, STO/E, STO/L and STO/EL) LIF. Scale bars: 500 mm. (B) RT-PCR analysis of genetic markers of the undifferentiated state. ES/iPS cells were cultured on the various feeder layers in LIF-free medium (MEF, STO, STO/E, STO/L and STO/EL). The control experiment (MEF+LIF) was performed by culturing ES/iPS cells on a MEF feeder layer in medium containing 1 × 103 U/ml LIF. (C) RT-PCR analysis of marker genes related to formation of the three germ layers. ES/iPS cells were cultured on a STO/EL feeder layer for 10 d in LIF-free medium. The control experiment (MEF+LIF) was performed by culturing ES/iPS cells on a MEF feeder layer in medium containing 1 × 103 U/ml LIF. ES/iPS cells were then cultured in suspension with differentiation medium to form EBs. After 11 d, the expression of marker genes was analyzed by RT-PCR.