PIK3CA and urinary bladder cancer: For example, phosphatidylinositol 3-kinase (PI3K) and Cyclin D kinase 4/6 (CDK4/6) inhibitors have been used against metastatic breast cancer [with PI3K catalytic subunit alpha (PIK3CA) mutations], and fibroblast growth factor receptor (FGFR) inhibitors have been used against bladder cancer (with FGFR3 mutations) (16–19).