DAPK1 and breast adenocarcinoma: Loss or failure in the recruitment of the multi-subunit Mediator complex for RNA polymerase II-dependent gene transcription Med1 and/or the transcription factor C/EPB-β (CCAAT/enhancer binding protein-β) to the CRE/ATF (cyclic-AMP response element/activating transcription factor) site of the DAPK gene promoter appears to be responsible for the loss of DAPK expression in human lung and breast adenocarcinoma cell lines.