Verapamil enhancement of SRC transduction. (A) Representative flow cytometric analysis at 6 to 8 weeks after primary transplant with stem cells that were transduced with 25 TU column-purified vector for 2 days in 75 μg/mL verapamil or without verapamil. (B) Flow cytometric analysis of a mouse that received a secondary transplant infused with cells that either were untransduced or were transduced with 25 TU column-purified vector for 2 days in 75 μg/mL verapamil or without verapamil. (C) Average percentage of transgene-expressing repopulating cells from mice during primary transplantation (left; n = 7, ▦;n = 8, □; ± SEM) and secondary transplantation (right; n = 2, ▦;n = 3, □; ± SD) in the presence (gray bars) or absence (open bars) of verapamil.