Clonogenic survival is increased for various RA and RG clones after IR exposure. Log-linear clonogenic survival curves for cells treated with γ-rays (A) or α-particles (B). (C) The low α-particle dose-response is displayed for RA5 and RG2. (D) Normalized survival to a single dose of ∼ 0.23 Gy α-particles is shown for select clones. *P < .05, relative to HL60. Data are mean ± SEM of at least 3 independent experiments