Coimmunoprecipitation of hsp90 and hsp70 with KIT protein. KIT protein was immunoprecipitated from HMC-1.1 and HMC-1.2 cells and associated hsp90 and hsp70 proteins were probed by Western blot analysis (A). Cells were treated with 1 μM 17-AAG for 1 hour. Protein G-Sepharose beads alone were used to exclude the possibility of nonspecific binding. Treatment with 17-AAG for 1 hour was chosen because of minimal change in total KIT levels during that time (B).