MTAP and cancer: This pathway requires the activity of methyladenosine phosphorylase (MTAP) as well as Met synthase (MS).234 MTAP is located in the periphery of the tumor suppressor cyclin-dependent kinase inhibitor 2 A (CDNK2A), and the co-deletion of the two genes occurs in ~15% of cancers and results in a highly aggressive tumor with a poor prognosis.