p21-Activated kinase (PAK)1 copy number and expression is elevated and associated with poor clinical outcome in breast tumors analyzed by the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC). (A) Illumina mRNA expression of PAK1 is correlated with copy number alteration and breast cancer subtype in METABRIC tissue samples. “Amplification” is defined as gene amplification greater than or equal to 5 copies, while “Gain” is defined as >2 and <5 copies. (B) PAK1 focal amplification is associated with poor patient prognosis. Hazard ratio coefficient (log2 scale) is plotted for clinical and molecular parameters. Hazard ratio is significantly higher for PAK1 focal amplification relative to CCND1 focal amplification or dual PAK1/CCND1 amplification in luminal breast tumors (n = 980). P values are shown. CCND1, cyclin D1; Decade, patient age at time of diagnosis; Lum A, luminal A; Lum B, luminal B; NPI, Nottingham prognostic index.