IFNB1 and melanoma: This consideration led to the hypotheses that (i) IFN-β treatment enhanced IRF6 expression in the melanoma cells with an unmethylated 5' IRF6 CGI, with the result that IRF6-associated tumor suppressors, including maspin and IRF6-induced endogenous IFNs, inhibit the growth of melanoma cells with an unmethylated 5' IRF6 CGI, and (ii) IFN-β treatment cannot induce IRF6 expression in the melanoma cells with methylated 5' IRF6 CGI, with the result that IRF6-associated tumor suppressors do not inhibit the growth of melanoma cells with a methylated 5' IRF6 CGI.