PAK4 and breast cancer: There is some research by constructing PAK4 eukaryotic expression vector and PAK4 ShRNA eukaryotic expression vector, transfecting breast cancer MDA-MB-231 cells, which showed that after up-regulation of PAK4 expression in breast cancer cells, it can significantly promote breast cancer cell proliferation; inhibit apoptosis; increase cell adhesion, movement, invasion, tumorigenesis, and other biological activity; and vice versa [10].