Related to Figure 5b and Figure S6. Matrix degradation is not required for PE opening.
Time-lapse confocal images (z-projections) of third-instar larval leg discs expressing fluorescent myosin (sqh-TagRFPt[9B], top) and collagen (vkg-GFP, middle) and cultured with ecdysone to induce leg elongation. Bottom row: merged images (collagen: cyan, myosin: magenta). Left: control condition (0.5% DMSO). Right: MMP inhibition (0.5% DMSO, 50 μM GM6001). Image stacks were acquired every 15 min. The ECM layer opens at the dorsal tip and retracts in the control condition, whereas MMP inhibition preserves ECM integrity at the dorsal tip. The PE cell monolayer opens and retracts in both conditions (control: n = 7/7, GM6001: n = 11/11).