English: PI3K Signaling Is Necessary for Cell-Cycle Progression during the Second Stage of Proliferation (18–27 h APF) Homozygous mutant clones for dp110 induced in the blastoderm (MARCM, labeled with GFP) and monitored during the second stage of histoblast proliferation (posterior dorsal nest). Wild-type cells were labeled by expression of a nuclear His2-YFP (red). At 18 h APF, a clone from a single precursor histoblast should include around 20 cells generated by three synchronous fast early divisions and one or two slow late divisions. The clone in the movie is initially composed of eight cells, indicating that the mutant histoblasts are already delayed in their entry in the slow stage and did not proceed through a fourth division yet. The entry in division of mutant histoblasts was compared to neighbor wild-type cells (dots). The histoblasts from the mutant clone enter division at a very slow pace (compared to wild-type neighbors) and some cells do not divide at all. In total, the clone reaches a size of 14 cells by 27 h APF.