Effects of signal transduction inhibitors on expression of Hsp32 in neoplastic cells. (A) HMC-1.2 cells were cultured in control-medium, the MEK inhibitor PD89059 (50 μM), the PI3-kinase inhibitor LY294002 (20 μM), a combination of PD89059 (50 μM) and LY294002 (20 μM), or the mTOR inhibitor rapamycin (20 nM) at 37°C for 24 hours. Then, cells were subjected to Western blot analysis using antibodies against Hsp32 or β-actin. (A) Ton.Kit.D816V-27 cells were starved (control) or were induced to express KIT D816V by exposure to doxycycline. KIT D816V-expressing cells were kept in control medium, PD89059 (50 μM), LY294002 (20 μM), a combination of PD89059 (50 μM) and LY294002 (20 μM), or rapamycin (20 nM) at 37°C for 18 hours. Then, cells were harvested and subjected to Western blotting using antibodies against Hsp32 or β-actin (loading control).