SOD1 and cancer: inhibited expression of KSR1, p-KSR1, ERK1/2 and p-ERK1/2enhancing the inhibition of tumor cell proliferationincreasing the induction of tumor cell apoptosisreduction of malondialdehyde (MDA) levels in cancer cellsincreased activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in cancer cells