SQSTM1 and neoplasm: On the contrary, p62 overexpression increases ROS and accelerates tumorigenesis in an autophagy-defective background, but not in an autophagy-competent one ( Mathew et al., 2009), suggesting that the tumor-forming abilities of autophagy-deficient cells may be dependent on persistent and abnormal p62 accumulation, which is the result of combined p62 induction in response to defective autophagy-associated oxidative stress and impaired p62 elimination, again due to deficient autophagy.