The sensitivity of leukemic cell lines to Pim kinase inhibitor SMI-4a. Human and mouse leukemic cell lines were incubated with the indicated concentrations of SMI-4a for 24 hours in serum-free medium and then viable cells were quantitated by trypan blue exclusion. (A) Human pre–T-LBL cell lines. (B) Human non-T leukemic cell lines. All cell lines except for Nalm 6 pre-B-LBL were derived from a myeloid leukemia. (C) The murine leukemic cell lines tested were established from pre–T-LBL (12/1. 6605/4, 6645/4, 6812/1, St4113) and erythroleukemia (F4-6).