Deletion of the chromosomal region 9p21 is often found in a variety of human tumors mainly in gliomas, leukemias, lymphomas, head and neck cancer, esophageal carcinomas, pancreatic carcinoma, bladder carcinoma, lung carcinomas, sarcomas and melanomas. The 9p21 region contains, inter alia, two genes: MTS1/p16-INK4 (p16) and MTS2/p15-INK4B (p15). These genes are known tumor suppressor genes which encode proteins that inhibit activity of cyclin-dependent kinases. Their deletion can lead to the loss of cell cycle control, resulting in uncontrolled cell growth. 9p21 apparently encodes another tumor suppressor genes which, however, have not been identified yet.
Investigation is performed by the use of interphase FISH using LSI® p16 (9p21) SpectrumOrange/CEP® 9 SpectrumGreenTM Probe1 (Vysis/Abbott) probe. The result of hybridization in the case of healthy tissue is the nucleus with two red and two green signals. When samples with 9p21 deletion, we observe one red and two green signals.
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