Previous studies on the mechanism of PAK4-enhanced tumor progression addressed several downstream effectors, such as c-Src, MEK-1/ERK1/2, MMP2, and c-Src/EGFR in ovarian cancer [10], p57Kip2 [22] and integrin αvβ5 [23] in breast cancer. This evidence concerns the gene PAK4 and breast carcinoma.