To evaluate levels of CIN85 expression in breast cancer cells, whole cell extracts were prepared from two untransformed lines: human MCF10A and mouse NMuMG cells and from nine breast cancer cell lines: human MCF7, ZR-75, T47D, Hs578T, MDA-MB-231, MDA-MB-231-derived LM2, BT474, and trastuzumab-resistant BT474-Clone E cells, and murine NF639. This evidence concerns the gene SH3KBP1 and breast cancer.