These, together with the observations that E2 and/or ICI had no effect on the expression of CXXC5 in ERα-negative MDAMB231 cells derived from a breast adenocarcinoma (data not shown), collectively suggest that the expression of the CXXC5 gene in MCF7 cells is E2- and ERα-dependent. This evidence concerns the gene ESR1 and breast adenocarcinoma.