Analysis of the PIAS1–Stat1 interaction in the modified yeast two-hybrid system. Shown is the growth of various yeast cells expressing LexA-JH1-Stat1β (A), LexA-JH1-Stat1β (Y701F) (B), LexA-JH1-Stat1β (R602L) (C), and LexA-JH1 (D) together with full-length PIAS1 (Upper), PIAS1c (Middle), and empty vector (Lower).