NFATC1 and breast cancer: Transcriptional regulation by NFAT factors in normal cell physiology most often involves their cooperation with unrelated transcriptional regulators,3 or their binding as homodimers to palindromic or close to palindromic response elements.22, 23 It is thus possible that critical NFAT-dependent genes in mammary tumor cells rely on the binding of NFAT1/NFAT2 heterodimers.