USP39 and neoplasm: Histological examination revealed that the tumor area in U87‐ov‐USP39‐bearing brain was larger than that in U87‐ov‐Con‐bearing brain at 25 days after cell injection (Fig. 8A); U87‐ov‐USP39 orthotopic xenografts tended to be more invasive than U87‐ov‐Con (Fig. 8B).