Pim-1 inhibits STAT5-dependent transcription in IL-3–stimulated FDCP1 cells. (A-B) FDCP1 cells stably expressing either neomycin (FD/Neo), the 44-kDa Pim-1 protein (FD/Pim44), or a kinase-deficient mutant of Pim-1 (FD/NT81) were transfected with the Spi-LUC2 reporter with or without wild-type (WT) or kinase-deficient (KN) 33-kDa Pim-1 protein (Pim33) as indicated. Cells were left unstimulated or stimulated with IL-3 as indicated. Luciferase activities from cell lysates were measured and normalized against cotransfected control vectors. (C) FD/Neo (▦) and FD/Pim44 (▪) cells were transfected with the NFAT-LUC or AP-1-LUC reporters as indicated and stimulated with PMA and ionomycin.