Figure 3

Pvf/Pvr signaling controls cell growth and G1/S progression. (a) FACS analysis of RNAi-treated S2R+ cells. Control cells typically exhibit a large G2 peak and a much smaller G1 peak. However, treatment with dsRNA to Pvf2/3, Pvr, Ras1 or Rheb causes a significant increase in the G1 peak with a concurrent decrease in the G2 peak. (b) BrdU labeling of cells treated with dsRNA targeting the Pvr/Ras pathway suggests that cells are still cycling. Parallel silencing of Cdc25 expression blocks cell cycle progression as expected. (c) Cdc25 (String) RNAi causes a significant increase in cell volume. This increase is suppressed by simultaneous silencing of Pvr or members of the Ras/MAPK pathway. (d) Chart of the mean percentage change in cell volume of RNAi treated S2R+ cells relative to control (LacZ RNAi) cells. Upstream components of the insulin signaling pathway do not affect cell size. However, downstream components (PDK1, Akt) exhibit a small effect. Silencing of negative regulators of both insulin (Pten) and Tor signaling (Tsc1/Tsc2) results in a significant increase in cell size. Conversely, silencing of positive regulators of Tor signaling reduces cell size. Error bars indicate the standard error of the mean.