USP44 and neoplasm: Although it has been reported that mice lacking Usp44 were prone to the development of spontaneous tumors due to the effect to mitotic checkpoint and chromosome lagging (Zhang et al, 2012; Mosbech et al, 2013), we observed that tumor growth was significantly slower in the Usp44‐null mice compared to their littermate, which suggests a complex role for USP44 biology in tumor‐bearing mice.