CXCR4 and prostate carcinoma: In addition, we found that co-expression of AIP4 resulted in a significant accumulation of ubiquitinated CXCR4 and subsequently suppressed CXCR4 protein levels, indicating that AIP4 inhibits the ligand-induced degradation of CXCR4 in TP53-deleted prostate cancer cells (Figure 4C).