As illustrated in Fig. 8a, the common somatic alterations targeting the cell cycle regulation in NPC are the homozygous deletion of 9p21.3 including the CDKN2A/CDKN2B loci in three PDXs (Xeno23, 47 and 76) and amplification of CCND1 on 11q13 in NPC43 cell line. This evidence concerns the gene CDKN2B and nasopharyngeal carcinoma.