As direct interaction between Rac1 and Pak1 or WAVE2 is not detected in breast cancer cells, it is reasonable to assume that βPIX, the Pak-interacting nucleotide exchange factor of Rac/Cdc42 [93], plays an important role in the signal transduction between Rac1 and Pak1. The gene discussed is WASF2; the disease is breast carcinoma.