Mitotic and apoptotic figures on sections from ISO and MUC4-oncotropic lentivector-injected tumors. Sections from tumors injected with ISO-oncotropic control lentivector (A) or with MUC4-oncotropic lentivector (B) were stained with hematoxilin. Mitotic figures (M) and apoptotic figures (A) were counted in 2791 (ISO) or 1558 (MUC4) cells (n = 3). **: p = 0.002 with Student’s t test. Original magnification X40.