The effect of ABL kinase inhibitor STI571 on DNA repair activity in p210 BCR/ABL-positive cells. DNA repair synthesis activity on UVC-damaged plasmid was examined with the extracts from (A) BaF3 and BaF3-p210 lymphoid cells and (B) 32D and 32D-p210 myeloid cells pretreated (+) or not (-) with 1 μM STI571, and (C) UT7-p210 pretreated for 24 hours with the indicated concentrations of STI571 (upper and middle panels). For more details, see Figure 1 legend. p210 BCR/ABL, phosphotyrosine proteins, and actin (loading control) expression were determined by Western analysis (lower panels). The * indicates difference between values for untreated and STI571-pretreated cells at P < .01, as determined by Student t test.