Figure 4.

Inhibiting P53 activity in USP4 knockdown cells resumes chemoresistance to TMF. (A) U251 and (B) U87 cells transfected with scramble or USP4 small interfering RNAs were treated with 100 µM TMZ with or without 30 µM PFT for 24 h, and then P53 and cleaved PARP levels were detected by western blotting. (C) U251 and (D) U87 cells were examined by flow cytometry analysis, and the results indicated that PFT treatment resumed the chemoresistance of USP4 knockdown cells to TMZ. USP4, ubiquitin-specific protease 4; TMZ, temozolomide; PFT, pifithirin-α hydrobromide; PARP, poly(ADP-ribose) polymerase.