Premature lysosome maturation in Yap/Taz mutant cells. (A) LAMP3 particles shift from small, scattered (arrowhead) to large, overlapping with BFP-Lamp1 (caret; BFP+) as developing AT2 cells (yellow) become mature AT2 cells (magenta). See also Fig. S5 A. Unrecombined cells have a white outline. AT1 cells may also be targeted by Sox9^CreER. More AT2 cells are in the Yap/Taz mutant (dash) and at a more mature stage. 500 μg tamoxifen was given at E13.5 for the control; 2 mg tamoxifen was given at E14.5 for the Yap/Taz mutant. Scale: 10 μm. (B) Normal temporal changes in lysosome size from progenitors at E16.5 (500 μg tamoxifen at E12.5) to AT2 cells at E18.5 (500 μg tamoxifen at E14.5) and P7 (300 μg tamoxifen at P1). Scale: 10 μm. (C) Quantification of LAMP3 particle volumes over time grouped by overlapping with BFP-Lamp1, showing an earlier increase in volume and a larger end volume in the Yap/Taz mutant. Asterisk, P < 0.05; ns, not significant (ordinary ANOVA with Tukey test; data are mean and standard deviation).