Figure 1. Sin3B stabilizes exogenously expressed Mad4. (A) SF767 cells were transfected with FLAG-Mad4, FLAG-mSin3B and empty vector (EV) such that the total amount of plasmid used in each treatment was equal. After 42 to 48 h, cells were lysed in sample buffer and protein expression was measured by western blot analysis using the indicated antibodies. (B) U251 or U373 cells were transfected with the indicated plasmids and lysed in sample buffer after 42–48 h. Protein expression was determined by immunoblotting. (C) U251, U373 and SF767 cells were transfected with 8 µg Sin3B or empty vector in addition to 1 µg GFP expression vector. After 72 h, protein expression was assessed by immunoblotting as indicated.