GRP and small cell lung carcinoma: Using a cut-off value for PAK6 (60.10 ng/L), NSE (3.01 ng/mL), ProGRP (53.1 pg/mL), CEA (2.83 ng/mL) and CA19-9 (13.15 U/mL) determined by X-tile, we divided the SCLC group into high and low STMs expression groups.