MAP2K7 and gastric cancer: MSC exosomes induce the resistance of gastric cancer cells to 5-fluorouracil both in vivo and ex vivo. MSC exosomes antagonise 5-fluorouracil-induced apoptosis and enhance the expression of multi-drug-resistance-associated proteins, including MDR, MRP, and LRP. MSC exosomes trigger the activation of calcium/calmodulin-dependent protein kinases (CaMKs) and Raf/MEK/ERK kinase cascade in gastric cancer cells. Blocking the CaM-Ks/Raf/MEK/ERK pathway inhibits the promoting role of MSC exosomes in chemoresistance.