A gene product of the p16 tumor suppressor gene (genes, p16). It antagonizes the function of MDM2 PROTEIN (which regulates P53 TUMOR SUPPRESSOR PROTEIN by targeting it for degradation). p14ARF is produced from the beta mRNA transcript of the p16 gene. The other gene product, produced from the alternatively spliced alpha transcript, is cyclin-dependent kinase inhibitor p16. Both p16 gene products have tumor suppressor functions.