S100A8 and gastric cancer: It is known that CagA is dominated by the activation of ERK and JNK subgroups, among the four major branches of ERK, JNK, p38 MAPK, and ERK5—where ERK is responsible for cell differentiation and growth—and Ras/Raf is its upstream signal, while JNK plays an important role in cell apoptosis and inflammation—both of which contribute to the progression of GC as a result of CagA [105].