While the MAPK/JNK and the MAPK/p38 signaling pathways are mostly related to the regulation of the immune response and are activated by cellular stress conditions (including the oxidative, genotoxic, and osmotic stress), the MAP/ERK signaling pathway plays a crucial role in cancer development by promoting cell proliferation and migration; this latter pathway is mainly activated by growth factors (reviewed in References [47,48]). Here, MAPK1 is linked to cancer.