To validate protein S-nitrosylation in pancreatic cancer pathway, a biotin-switch method was performed to test the S-nitrosylation of Raf-1 and STAT3 proteins in non-neoplastic human pancreatic ductal epithelium cell line HPDE6c7 and two PDAC cell lines PANC-1 and SW1990. The gene discussed is STAT3; the disease is pancreatic neoplasm.