Bosutinib is selective for Src over non-Src family kinases with an IC50 of nM, and potently inhibits Src-dependent cell proliferation with an IC50 of 100 nM.  Bosutinib significantly inhibits the proliferation of Bcr-Abl-positive leukemia cell lines KU812, K562, and MEG-01 but not Molt-4, HL-60, Ramos, and other leukemia cell lines, with IC50 of 5 nM, 20 nM and 20 nM, respectively, more potently than that of STI-571. Similar to STI-571, Bosutinib displays antiproliferative activity against the Abl-MLV-transformed fibroblasts with IC50 of 90 nM. Bosutinib ablates tyrosine phosphorylation of Bcr-Abl and STAT5 in CML cells and of v-Abl expressed in fibroblasts at the concentration of ~50 nM, 10-25 nM and 200 nM, respectively, leading to the Bcr-Abl downstream signaling inhibition of Lyn/Hck phosphorylation.  Although unable to inhibit the proliferation and survival of breast cancer cells, Bosutinib significantly decreases the motility and invasion of breast cancer cells with IC50 of ~250 nM, involved with an increase in cell-to-cell adhesion and membrane localization of β-catenin.