Clonogenic survival for (A, B) MDA-MB-468 and (C, D) 231-H2N cells. Cells were incubated with suberoylanilide hydroxamic acid (SAHA) followed by (A, C) IR, (B, D) 111In-DTPA-hEGF (30 MBq/μg; 100 pM or 0–67 MBq/μg; 12 nM, respectively) or DTPA-hEGF (100 pM or 12 nM). Results are means ± SEM of three experiments or means ± SEM of triplicates in one experiment. Error bars are too small to be seen in (A and D).