USP22 and Familial prostate cancer: These authors also reported down regulation of the Heat shock protein family A (Hsp70) member 5 (HSPA5), an HSP70 family member involved in the unfolded protein response, in tumors from Usp22 null mice, consistent with reports that USP22 mediates deubiquitination of HSPA5 in human prostate cancer cells [15].