摘要篇首： The long arm of human chromosome 12 contains a region that has been found to be amplified in a number of different tumors, including osteosarcomas and soft tissue sarcomas,1 There are more than 5 genes located in this area such as CDK2, CDK4, WNT1, MDM2 and WNTIOb.1 CDK4 gene consists of eight exons, of which the start codon is located in the beginning of exon 2 and the stop codon in the beginning of exon 8. CDK4 is a member of the Ser-Thr protein kinase family and its catalytic domain extends from amino acid 6 to 295. CDK4 is expressed in a variety of normal cells and tissues as well as in cancer cells. CDK4 constitutes the catalytic subunit of a heterodimeric Ser/Thr protein kinase that is involved in controlling progression through the G1 phase of the cell cycle. Germ-line mutations in the CDK4 gene have so far only been found in families with inherited malignant melanoma and multiple atypical nevi. The mutations affect the Arg encoded by codon 24, changing it either to Cys or to His.