MAPK8 and gastric cancer: Among the four major branches of ERK, JNK, p38 MAPK, and ERK5, CagA is dominated by the activation of ERK and JNK subgroups, among which ERK is in charge of cell growth and differentiation, and its upstream signal is the well-known Ras/Raf protein, while JNK is mostly involved in cell inflammation and apoptosis, both of which are critical for CagA-induced GC progression (Cargnello and Roux, 2011).