CCND1 and cancer: Furthermore, other report demonstrated that ANT2 as well as another major ANT isoform ANT3 did not mediate mitochondrial ATP/ADP exchange in cancer cells.54 Thus ANT2-mediated ATP/ADP exchange appears to be dependent on cellular context, and cyclin D1 expression may be regulated by a noncanonical ANT2 function independently of intracellular ATP levels in cancer cells, although further investigation should be required to unravel the more precise mechanism.