Quantitative RT-PCR for Oct4 in whole-culture (*) and micro- (**) XEN-P cell line samples.

Samples (numbers in brackets) were RNA-extracted, RNA preparations were DNAse-treated and quantified in duplicate by real-time RT-PCR using dual-specific (mouse = rat) primers; controls without reverse transcriptase did not yield a product. Data (Means±SEM) were normalized to Hprt mRNA and expressed as fold of the level in ES cells, i.e. ES cell level is set as 1. A, B, two groups of microsamples with high and moderate Oct4 mRNA expression, respectively. Two experiments labeled C were corrected for feeder cell RNA; the other measurements are slight underestimates.