ERBB2 and breast cancer: The synergistic effect observed in Her2 positive cells was not surprising, due to the fact that Pak1 is an essential mediator of Her2 signaling in mammary tumors, and some reports suggest that combined inhibition of Pak1 and some other relevant oncogenes such as BCR-ABL1, Akt, β-catenin and Aurora A might be useful for treating cancers driven by oncogenes for which Pak1 is thought to be an obligate signaling element (Arias-Romero et al., 2013; Walsh et al., 2013; Flis et al., 2019; Korobeynikov et al., 2019).