CDKN1B and pachyonychia congenita: The contribution of NDRG1 to the metastatic phenotype of E6AP does not exclude the contribution of other known targets of E6AP potentially, including PML, p27Kip1, and Clusterin, all of which are tumor suppressors whose expression is partially or completely lost in aggressive and metastatic PC, among other cancers (3,4,9).