Immunohistochemistry (IHC) analysis of the expression of prostaglandin-endoperoxide synthase-2 (PTGS2), a marker for the assessment of oxidative stress and ferroptosis in vivo, indicated the combination effect of knocking down USP8 and erastin treatment in triggering tumor ferroptosis in vivo (Fig. 1L). This evidence concerns the gene PTGS2 and neoplasm.