Kaposis's sarcoma: A rare type of skin cancer sometimes found in elderly people or people with weak immune systems. Patients with acquired immune deficiency syndrome (AIDS) most often develop this skin cancer. Karnofsky performance: A measure given by a physician to a patients ability to perform certain ordinary tasks: 100-normal, no complaints, 70-unable to carry on normal activity, 50-requires considerable assistance, 40 - disabled, 30 - hospitalization recommended. kDa: Kilo dalton, a measure of molecular mass of protein. Keratinocyte: The epidermal cell which synthesizes keratin, a protein that is the principal constituent of skin, hair, nail, and organic matrix of the enamel of the teeth. Keratosis: Any horny growth, such as a wart or callosity. Kidney glomeruli: The functional unit of the kidney is the nephron. Each kidney is composed of about one million nephrons. The nephron begins at blind end containing a cluster of blood capillaries known as glomerulus. Kinase: A class of enzymes that catalyzes the transfer of high-energy phosphate group from a donor compound such as ATP or GTP to an acceptor compound such as alcohol, carboxyl, nitrogenous group or another phosphate group. Klinefelter's syndrome: A genetic disease of male with more than one X chromosome characterized by small testes. Some of the clinical features of this syndrome are mental retardation, increased frequency of diabetes mellitus, variable degrees of masculinization, infertility, and rare skeletal deformities. They are found to have poor DNA repair system. K-ras: A proto-oncogene that has point mutations and is associated with melanoma, thyroid carcinoma, and acute myelogenous and lymphoblastic leukemia. Kreb's cycle: Also known as tricarboxylic acid cycle; pathways by which organic materials are broken down by enzymatic reaction to produce carbon dioxide and water, leading to the production of high energy phosphate ATP.