04. Li Fernández Salazar

GIST tumors are the most frequent mesenchymal tumors in the gastrointestinal tract (1,2). There are between 10 and 20 cases per million in developed countries, and between 20 and 45% of them are malignant (3-5). These tumors are characterized by the expression of the membrane receptor c-KIT/CD 117 with tyrosine-kinase activity, synthesized from proto-oncogene c-KIT (1-6). The cKIT and CD 34 expression, that is usual in these GIST tumors and interstitial cells of Cajal, and their ultrastructural similarities have led to consider that their origin may be in these cells or their predecessors (2,6,7). The cKIT receptor is essential in identifying GIST, its molecular carcinogenesis grounds, and -response to treatment with imatinib mesylate (1-3,7-9).