PD173955 is a potent Bcr-Abl, Src and Yes inhibitor. When tested with CML CD34+ GM progenitors, PD173955 inhibited KL-dependent proliferation at an IC50 value of 50 nM and GM-CSF-dependent cell growth at an IC50 value of 1μM and the maximum inhibition was achieved at the dose of 25 nM. It was shown that PD173955 reduced the fractions of cells in G2-M phase and increased the cells in G1 phase with significant difference . In HT29 cells, PD173955 treatment inhibited Src auot-phosphorylation in a dose dependent manner. Further, PD173955 showed inhibition on cell growth with IC50 value of 800 nM without morphologic changes and high concentrations arrested cell cycle at the M phase . When tested with Bcr-Abl-depedent cell lines K562 and RWLeu4, PD173955 showed inhibition on cell proliferation with the IC50 value of 35 and 10 nM, respectively and arrested cell cycle in G1 phase at the low nanomola