In addition, pharmacologic unmasking experiments using the DNA methyltransferase inhibitor 2′-deoxy-5-azacytidine (DAC) resulted in re-expression of CD38 in a subset of cell lines with dense CD38 CpG island methylation (Additional file 3), further supporting the notion that CD38 expression is at least partially regulated by CpG methylation in prostate cancer. Here, CD38 is linked to prostate cancer.