Drosophila myc regulates cellular growth during development

Transcription factors of the Myc proto-oncogene family promote cell divisio n, but how they do this is poorly understood. Here we address the functions of Drosophila Myc (dMyc) during development. Using mosaic analysis in the fly wing, we show that loss of dMyc retards cellular growth (accumulation o f cell mass) and reduces cell size, whereas dMyc overproduction increases g rowth rates and cell size, dMyc-induced growth promotes G1/S progression bu t fails to accelerate cell division because G2/M progression is independent ly controlled by Cdc25/String. We also show that the secreted signal Wingle ss patterns growth in the wing primordium by modulating dMyc expression. Ou r results indicate that dMyc links patterning signals to cell division by r egulating primary targets involved in cellular growth and metabolism.