Biomarkers and driver mutations for diagnosis and prognosis of Pin 1-associated diseases are disclosed. In one embodiment, the methods for diagnosis of Pin 1-associated diseases may include detecting the level of Pin1 to stage abnormal cell growth, such as breast or prostate cancer. In another embodiment, the methods include evaluating the efficacy of a treatment of abnormal cell growth, such as cancer, by monitoring the levels of Pin1. In another embodiment, the methods include using driver mutations to determine the pharmacogenetics of abnormal cell growth, such as cancer. In the present disclosure, elevated active monomeric Pin1 levels may be detected by Pin1 biomarkers, which may include Pin1 Q33K or E100D driver mutations, Pin1 protein or transcript overexpression, dephosphorylation of Pin1 on Ser71, dephosphorylation of S16, phosphorylation of S65, phosphorylation of S138, deacetylation of Pin1 on K13 and deacetylation of K46, and / or desumoylation of Pin1 on K6 and desumolation of K63, among others.