Fig. 2. Amphibian PouV proteins can support mouse ES cell self-renewal. (A) The indicated PouV cDNAs were co-transfected with the Fgf4 enhancer or the octamer-binding motif luciferase reporters. Fold induction represents the increase in transcription compared with the vector-only control. Experiments were carried out in triplicate. (B) Morphology of day 9 puromycin resistant colonies transfected with the indicated cDNA in the presence or absence of Oct4 transgene expression. Colonies are stained for AP activity (red). Scale bars: 100 µm. (C) Rescue index for PouV proteins. The rescue index=the number of ES cell colonies in the absence of Oct4 /number of ES cell colonies in the presence of Oct4. Mouse Oct4 was assigned a value of 1 to which all other values were normalized. Data represents the mean values obtained from three independent experiments.