Functional analysis of Drosophila developmental genes instrumental in tumor suppression.

Of the 28 presently known Drosophila tumor suppressor genes we present the status of the functional analysis of the following three genes: (a) lethal (3) malignant brain tumor [1(3)mbt], which by homology belongs to the Pc-G gene family and may be involved in the stable silencing of specific developmental genes by changing the chromatin structure, and thus establishing and maintaining the differentiated state; (b) lethal (3) malignant blood neoplasm-1 [1(3)mbn-1], for whose function only vague predictions can be made; 4) benign (2) gonial cell neoplasm [b(2)gcn], which may function as a splice factor. Each Drosophila tumor suppressor gene transforms in the homozygously mutated state either one or two specific cell-types in a single step, and is thus the primary cause for tumorigenesis. For one of the genes a putative human homologue has been found.