Methods for inhibiting growth or proliferation of breast cancer cells are provided. The methods include administering to a subject in need thereof in an amount that is effective to inhibit growth or proliferation of the breast cancer cells a MELK inhibitor, wherein the breast cancer cells are estrogen receptor (ER) negative. In some aspects, the methods include administering to a subject in need thereof in an amount that is effective to inhibit growth or proliferation of the breast cancer cells a MELK inhibitor, a FoxM1 inhibitor or a MELK inhibitor and a FoxM1 inhibitor, wherein the breast cancer cells are estrogen receptor (ER) negative. Methods of treatment for breast cancer and methods of identifying patients having cancer that are likely to benefit from treatment with a MELK inhibitor, a FoxM1 inhibitor or a MELK inhibitor and a FoxM1 inhibitor are also provided.