FIGURE 2.

Treatment with HDAC, p38, and ATM inhibitors sensitizes A431/CCKBR cells to ²²⁵Ac-PP-F11N. Cell viability 48 h after treatment with ²²⁵Ac-PP-F11N alone or in combination with HDAC inhibitor TMP269 (A), ATMi AZD1390 (B), and p38i SB202190 (C). Bars represent mean ± SD. Corresponding combination index values between 0.9 and 1.1 indicate additive effects, and below 0.9 indicates synergism. (D) Western blot analysis for phosphorylation of HDAC9, HDAC4, and HDAC5 at S246, S259, and S220, respectively; p53 at S15; and p53BP1 at S1778 in protein lysates isolated from treated and control cells. Western blots were reprobed with antibody against GAPDH. *P < 0.05. **P < 0.01. ***P < 0.001.