Induction of Blimp-1 and METS/PE1 mRNA by ICSBP. (A) Expression of Blimp-1 and METS genes in ICSBP/ER-transduced Tot2p210 cells. RNA from cells treated with 1 μM β-estradiol for the indicated time was subjected to semiquantitative RT-PCR (for Blimp-1) and RNA blot analysis (for METS). (B) EMSA detection of DNA binding activity of Blimp-1. Nuclear extracts from ICSBP/ER-transduced Tot2p210 cells with or without estradiol treatment (10 hours) were analyzed with the PRF probe. In lanes 3 and 4, extracts from estradiol-treated cells were preincubated with anti-Blimp-1 serum, normal rabbit serum, or 100-fold excess unlabeled probe, prior to addition of labeled probe. (C) Effect of cycloheximide (CHX) on ICSBP/ER induction of Blimp-1 and METS transcripts. Cells were treated as in Figure 5D.