TP53 and Miyoshi myopathy: The CDKN2A genetic locus encodes the proteins p14 and p16; p14 activates p53 by rescuing it from proteasome-mediated proteolysis, whereas p16 antagonizes the cyclin-dependent kinases 4 and 6, consequently blocking cell cycle progression.42, 43 Although the TP53 gene is rarely inactivated in MM,13, 16 our observation of multiple p53 isoforms with variable expression levels in primary cell lines emphasizes an inter-patient variability characteristic of MM.