CDKN2B and neoplasm: For example, a study of NMR cells showed that, compared with human and mouse cells, they express a unique INK4 subtype, pALTINK4a/b, which is composed of the first exon of p15INK4b and the second and third exons of p16INK4a; compared with p15INK4b and p16INK4a, pALTINK4a/b inhibits cell growth more effectively and may contribute to tumor resistance in NMRs [12].