RAC1 and cancer: Although these data are the first (to our knowledge) linking mTORC2/Rictor to Rac1-mediated invasion and metastasis in spontaneous breast cancer models, Rictor-to-Rac1 signaling has been previously identified in cancers originating from other tissues [28–30], and previous studies have shown that HER2-amplified breast cancer cells use p120 Catenin-to-Rac1 signaling to promote breast cancer metastasis [31].