As shown in Figure 4C, most of the Usp22/Parkin positive palisade cells closely surrounding the necrosis were Ki67 negative and the frequency of Ki67 positive nuclei was higher in the more external layers, thus suggesting that palisade structures provide a proliferative advantage to the tumor cells possibly due to overexpression of Usp22 and induction of mitophagy. This evidence concerns the gene PRKN and neoplasm.