MAPK3 and cancer: Indeed, several evidence suggests that ROS, or more generally a pro-oxidative state, within cells act as second messengers in intracellular signaling cascades which induce and maintain the oncogenic phenotype of cancer cells, due to their ability to increase cell proliferation, survival, cellular migration participating in the Ras-Raf-MEK1/2-ERK1/2 oncogenic signaling, and also by inducing DNA damage leading to genetic lesions that initiate tumorigenicity and sustain subsequent tumor progression [39].