PAK1 and breast carcinoma: To identify differentially regulated genes between wild-type and PAK1 deficient mouse and human breast cancer cells, we extracted total RNA from the genetically engineered human cell line MCF10A.B2 expressing an inducible shRNA against PAK1, and from PAK1−/− breast cancer cell lines derived from murine tumors [14], and performed a comparative gene profiling study by using human or mouse whole genome arrays.