It has been reported that progesterone38 and aryl hydrocarbon receptor39 upregulate ABCG2 expression, whilst DNA methylation represses ABCG2 expression in human renal carcinoma,41 and in multiple myleoma cell lines.42 Cytokines and growth factors have also been reported to alter the expression of the ABCG2. Here, ABCG2 is linked to renal carcinoma.