Pim-1 inhibits STAT5-dependent transcription in PRL-stimulated HC11 cells and in EPO-stimulated HeLa cells. HC11 (A) and HeLa (B) cells were transfected with the Spi-LUC2 reporter and STAT5A expression vector with or without WT or KN Pim33. EPO receptor expression vector was also transfected into HeLa cells. Starved cells were left unstimulated or stimulated with PRL (A) or EPO (B) as indicated.