GDF15 and gastric cancer: In Cox-2-deficient gastric cancer cells, celecoxib induces caspase-dependent apoptosis via the Akt/GSK3β/NAG-1 pathway; it inhibits Akt phosphorylation, and GSK3β, a downstream target of Akt, and upregulates NAG-1 expression, a pro-apoptotic and anti-tumorigenic protein [44].