Long-term maintenance of St-T1b cells. A) St-T1b cells, obtained at passage number 30, were kept in continuous culture for the indicated number of passages and tested for their ability to decidualize in response to 3 d of 8-Br-cAMP stimulus. Transcript levels of dPRL, IGFBP-1 and FOXO1 were determined by RT-PCR; GAPDH mRNA was amplified for normalization. B) St-T1b cells at passage number 44 or 114 were treated with the indicated combinations of 8-Br-cAMP, P4 (1 μM) and E2 (10 nM) for 7 d before Western blot analysis for FOXO1. The blot was stripped and reprobed with GAPDH antibody. C) St-T1b cells at passage number 114, untreated or treated with 8-Br-cAMP for 7 d, were subjected to immunocytochemistry with vimentin antibody (original magnification, 100×).