FIGURE 2.

PTIP accumulates PA1 at DNA damage sites. A, PTIP and PA1 form foci after DNA damage. SFB-PTIP 293T stable cell lines or U2OS cells grown on coverslips were treated with 10 Gy IR, 100 μg/ml mitomycin (MMC), 25 nm camptothecin (CPT), or 2.5 μm VP16. 8 h later cells were fixed, and immunostaining was carried out using indicated antibodies. B, U2OS cells with PTIP knockdown (shPTIP#1, shPTIP#2) or transfected with control vector (shCTR) were irradiated (10 Gy), allowed to recover for 6 h, fixed, and immunostained using antibodies as indicated. Western blot analysis was performed to verify the stable knockdown of PTIP (right panel).