Transgenic DPP-IV overexpression led to increased EGF-induced colony formation in normal breast epithelial cells and facilitated EGF signaling via MEK/ERK and JNK/c-Jun, leading to the expression of peptidylprolyl cis/trans isomerase-1 (PIN1) and cyclin D1 in cancer cells. The gene discussed is DPP4; the disease is cancer.