CFTR and breast adenocarcinoma: For example, studies on mouse mammary adenocarcinoma cells expressing human cystic fibrosis transmembrane conductance regulator (CFTR, a phosphorylation and ATP-gated anion channel) have shown that brief exposure to CYT-D significantly enhances the channel conductance for Cl- in the current–voltage curve to the extent that is comparable to the time when the channel is activated by adenosine 3’,5’-cyclic monophosphate (cAMP), the second messenger activating protein kinase A (PKA) [99].