CCND1 and cancer: Recently,an increasing number of studies have been devoted to investigate thepolymorphisms in a variety of cancer-related genes for their potentialinfluence on NPC susceptibility, including matrix metalloproteinases (MMPs) [50, 51], transforming growthfactor-beta1 (TGF-beta1) [52], interleukin-10 (IL-10) [53], antigen processing 1 gene(TAP1) [54], p53 [55], cyclin D1 (CCND1) [56], FAS (CD95) [57], mouse double minute 2 (MDM2)[58], and Nedd4 binding protein 2 (N4BP2) [59].