DNA-binding activity of STAT5b and STAT5b preys in Hek293-Flp-In cells detected by EMSA. EMSA experiments using a STAT5 probe derived from the β-casein promoter and nuclear extracts of Hek293-Flp-In cells transiently transfected with different bait constructs or the EpoR-LepRF3 and the wild-type STAT5b (A) or full-length STAT5b prey (B). Lanes A2 and A4: super-bandshift assay using a STAT5 antibody. Lanes B2 and B4: super-bandshift assay using a FLAG antibody. In panel C, Hek293-Flp-In cells were transfected with the Y402 bait and the STAT5b prey (lanes 1-4) or Y699F STAT5b prey (lanes 5-6). In lanes 1 and 5, cells were left untreated, in all other lanes cells were treated with Epo. Lanes 3 and 4: super-bandshift using STAT5 and FLAG antibody, respectively.