Transcription factor expression and growth factor responsiveness of type I yolk sac precursor cells.

(A) Total RNA (30 μg) was resolved in 1% agarose formaldehyde gels and transferred onto nylon membranes. The membranes were hybridized with α-³²P-deoxycytidine triphosphate (dCTP)–labeled cDNA probes as indicated and the blots were visualized using a Storm860 phosphorimager (Molecular Dynamics, Sunnyvale, CA). Representative of the data obtained from 2 cell lines. (B) Colonies generated from 3000 cells in serum-free methylcellulose medium containing a serum substitute (BIT, from Stem Cell Technologies, Vancouver, BC, Canada) and VEGF (25 ng/mL), bFGF (50 ng/mL), IL-6 (25 ng/mL), SCF (25 ng/mL), or cytokine combinations. The colonies were scored after 14 days of incubation. Representative of 2 independent experiments with 3 cell lines.