To further investigate the functions of Rack1 on the metastatic potential of drug-resistant breast cancer cells in vivo, we used pulmonary metastasis model in NOD-SCID mice via tail vain injection of MCF-7/ADR cells, control, and the Rack1 stable knockdown cells, as well as the Rack1WT- and Rack1Y246F-rescued cells. This evidence concerns the gene RACK1 and breast cancer.