English: Ras Signaling Is Not Required for Histoblast Proliferation during the Early Cell Cycles (1–8 h APF) A single mutant cell for the Ras-GEF son of sevenless (sos) (anterior dorsal nest) was induced in the blastoderm by mitotic recombination and labeled with GFP (green) using the MARCM system. Wild-type cells were labeled by expression of a nuclear His2-YFP (red). The mutant cell initiates the early cell cycles in synchrony with the wild-type histoblasts and divides three times to form a clone composed of eight cells at 8 h APF. Note that the third division (as the mutant cell approaches the transition to the second stage of proliferation) is slightly delayed compared to wild-type neighbors.