Cell proliferation assay

Cell proliferation assay was performed using MTT assay as described in our previous reports ^{18, 19}. Two hundred microliters of cell suspension (2×10⁴ cells/ml) were seeded in 96-well plate, and incubated together with various concentrations of ZSTK474 or Imatinib for 48 h at 37℃. After addition of MTT, the cells were further incubated for 4 h and dissolved in DMSO. The resulting absorbance at 490 nm was measured by microplate reader iMark (BIO-RAD, Hercules, CA, USA).