IMGN529 conjugate induces G₂/M cell cycle arrest. (A) Cell cycle profiles of BJAB cells after treatment with 10 nM of IMGN529 for 20 hours followed by staining with PI. G₁ and G₂/M peaks indicated in black and S phase as a hatched area. (B) Percentage of BJAB cells in G₁, S or G₂/M phase after treatment with 10 nM of indicated agents for 20 hours followed by PI staining. Results are shown as mean and standard deviation obtained from duplicate samples. (C) Caspase-3/-7 activity measured in DOHH2 and Farage cells after 1 day of treatment with 10 nM of indicated agents. (D) High-performance liquid chromatography radiogram and structure of the in vitro catabolite of ³H-IMGN529 formed within cells after 22-hour incubation.