TSPAN9 and gastric cancer: Previous studies also revealed that high expression of TSPAN9 is an independent prognostic factor for poor overall survival of patients with gastric cancer [86] and showed that TSPAN9 is overexpressed in 5-fluorouracil (5-FU)-resistant gastric cancer cells, where it contributes to the chemoresistance to 5-FU by promoting autophagy [87].