USP22 and breast cancer: The estrogen receptor pathway was found to be upregulated in our transcriptomic analysis; however, we were unable to observe any change in the levels of c-MYC protein in tissues or NMuMG cells overexpressing Usp22. While this manuscript was in preparation, a new study using breast cancer mouse models and human cell lines showed that Usp22 is necessary for the oncogenic function of HER2 and identified the deregulation of unfolded protein response (UPR) as the potential underlying mechanism [35].