Elicitation of apoptotic responses in BLs by bortezomib. (A) Immunoblotting detecting Hdm2 levels in lysates of BL Ly 91, Ly47, Ag876, and Ramos, and lymphoblastoid cell lines GM607 and LCL1. (B) Immunoblotting detecting p53 levels in Ly47 and Ramos cells in vitro. Ly47 cells were additionally infected with either empty vector or the E6-encoding retrovirus. Bar graphs below blots represent quantitation of p53-specific bands. (C) TUNEL staining of Ly47 and Ramos tumors from mice treated with bortezomib or vehicle alone. (D) Quantitation of tumor cell apoptosis. Bars refer to average numbers of TUNEL⁺ cells per microscopic field. No less than 4 fields were counted for each tumor specimen. Error bars represent SD. The asterisk refers to a statistically significant difference in apoptosis between Ly47/vector and Ly47/E6 tumors.