Since we have previously shown that PAK1, in response to PRL, increases the breast cancer cells migration and invasionin vitro(Hammer & Diakonova, 2016; Hammer et al., 2015; Hammer et al., 2013; Rider et al., 2013); reviewed in(Hammer & Diakonova, 2015)and (Carrasco-Ceballos et al., 2023)) as well as metastasisin vivo(Hammer & Diakonova, 2016), we focused the present study on the role of pTyr-PAK1 in regulation of EMT. The gene discussed is PRL; the disease is breast cancer.