CDKN1A and head and neck squamous cell carcinoma: However, recent reports have shown that the induction of p21-dependent senescence using the NEDD8-activating enzyme inhibitor, MLN4924, can work as a mechanism of growth suppression in multiple cancer cell lines.39 In addition, histone deacetylase inhibitors can sensitize mutp53 HNSCC cells to radiation through p21 induction (A. Fitzgerald and J. Myers, unpublished observations).