Greater sensitivity of ABPCs to STI-571 than TEPCs. A. Cell proliferation analysis of PCTs after treatment with STI-571. Five different cell lines including two ABPCs (ABPC20, ABPC22), two TEPCs (TEPC1165, TEPC 2027) and one pre B v-Abl lymphoma were treated with different concentrations of STI-571 at an initial concentration of 5 × 103 cells/well. Cell numbers were measured at 4 different times (0, 2, 4, and 7 days after treatment). B. Western blot analysis of PCTs for STAT1 phosphorylation and STAT3 phosphorylation. Samples for western blot were collected from untreated cells and cells after treatment with 5 μM STI-571 for 18 hours. Doublet bands are the α and β forms of the STAT proteins.