Abstract: Objective To investigate the role of SRC kinase inhibitor PP2 in drug resistance to adriamycin (ADM) in breast cancer cells and invasion, metastasis of cells. Methods MTT assay was used to detect the inhibitory effect of ADM on MCF-7 and MCF-7/ADM cells. The 50% inhibitory concentration (IC₅₀) and resistance index (RI) of cells were calculated. The expression of MDR1, connexin 43 (Cx43) and SRC proteins in breast cancer cells were detected by Western blot assay. Transwell experiment and cell scratch test were used to determine the invasion and migration of cells respectively 〔MCF-7, MCF-7/ADM, PP2 (1, 2, 4 μmol/L)〕. Standard colony formation assay was used to detect the cytotoxicity effect of 4 μmol/L PP2 pretreatment on ADM. Results ADM inhibited the proliferation of MCF-7 more than MCF-7/ADM cells (P<0.01). The IC₅₀ of MCF-7/ADM cells was 24.55 μmol/L, the IC₅₀ of MCF-7/ADM cells was 770.57 μmol/L, the RI was 31. Compared with MCF-7 cells, expressions of the multidrug resistance proteins MDR1 and SRC were significantly increased (P<0.01). The invasion and migration ability of the MCF-7/ADM cells was stronger than that of the sensitive cells (P<0.01). When MCF-7/ADM was exposed to SRC inhibitor PP2, the invasion and metastasis ability of cells were inhibited (P<0.01) and the rate of colony formation was decreased, that is, more sensitivity to ADM (P<0.01). Conclusion The resistance of MCF-7 to ADM is accompanied by increased expression of SRC. SRC inhibitor PP2 can reduce the cell resistance, ability of invasion and metastasis.