(A) Representative sum intensity projection images showing the localization and total levels forminCYK-1::GFP at the division plane in ABa and ABp (left panel), EMS (center panel), and P2 (right panel). Images were acquired after observation of the onset of contractile ring constriction (initial furrowing). (B) Schematic showing how forminCYK-1::GFP levels were measured along a line scan across the division plane. (C) Graph showing all four cells show a local peak of intensity of forminCYK-1::GFP at the division plane in the sum projection, and no increase is observed in EMS or P2 relative to in ABa/ABp. However, as expected, the sum intensity signal scales roughly with cell volume, with approximately equal levels in ABa and ABp, lower levels in EMS, and the lowest total levels in P2. (D) Schematic showing how forminCYK-1::GFP levels at the division plane were measured. (E) Graph showing the average summed fluorescence intensity of forminCYK-1::GFP at the division plane is not significantly different in ABa compared to ABp, but is significantly lower in both EMS and P2; and thus roughly scales with cell volume, as expected. Two-tailed t-test (Supplementary file 1); n.s., no significance, p>0.05; *p≤0.05; **p≤0.01; ***p≤0.001; ****p≤0.0001. Error bars, mean ± SEM; temperature, 21°C; scale bar = 10 µm.