Evidence showed that DPP-4 overexpression led to increased epidermal growth factor-induced colony formation and expression of peptidylprolyl cis/trans-isomerase-1 (PIN1) and cyclin D1 in cancer cells via MEK/ERK and c-Jun N-terminal kinase (JNK) pathway, thus causing epithelial-mesenchymal transition (EMT) and tumorigenesis in breast cancer [119]. The gene discussed is DPP4; the disease is cancer.