Inhibition of TEL/ARG autophosphorylation by STI571.

TEL/ARG was immunoprecipitated from TEL/ARG-transfected Ba/F3 cells cultured in the absence or presence of STI571 for 24 hours (lanes 1 and 2, respectively). An anti-PAC1 polyclonal goat antibody was used to immunoprecipitate the phosphatase PAC1 as a nonspecific control (lane 3). Protein lysate from TEL/ARG-Ba/F3 cells was also incubated in the presence of protein G beads alone, as a nonspecific control (lane 4). Immunoblotting was performed on all samples with anti-pTYR (upper panel) and anti-ARG (lower panel). Whole cell lysates from TEL/ARG-Ba/F3 cells cultured in the absence and presence of STI571 (lanes 6 and 7, respectively) were run in parallel with the immunocomplexes, and immunoblotting was similarly performed on these samples with anti-pTyr (upper panel) and anti-ARG (lower panel). Whole cell lysate from Ba/F3.p210 cells was run alongside whole cell lysates from TEL/ARG-Ba/F3 cells for comparison (lane 5). IP indicates immunoprecipitation.