Fig. 4.

β-TrCP1 interaction with and ubiquitination of p53. (A) 293T cells were cotransfected with Flag-p53 WT or AA and Myc β-TrCP1 WT or ΔF. Cell lysates were immunoprecipitated with antibodies to Myc or Flag. (B) Cell lysates were treated with phosphatase (CIP) for 30 min at room temperature before immunoprecipitation. (C) Similar immunoprecipitation was done in siGL3 or siIKK2 stably infected 293T cells. (D) 293T cells were cotransfected with Flag-p53, HA-ubiquitin, and Myc β-TrCP1 WT or ΔF. Then, 24 h after transfection, cells were treated with doxorubicin and lactacystin for 18 h. p53 proteins were immunoprecipitated and ubiquitination was checked by HA antibody.