G6PD and nonpapillary renal cell carcinoma: Additionally, it has been proved that ROS can activate MMPs or regulate MMP9 mRNA stability and lead to the destruction of extracellular matrix and facilitate tumor metastasis 19, 42, which promote us to hypothesize that facilitated MMP9 activation in ccRCC may also be induced by the G6PD-mediated ROS accumulation.