(A) Representative examples of FACS dot plots of single-cell suspension from the IFE epidermis of WT and GNAQQ209L mice. (B) Average percentage of tdTomato+ cells sorted from the IFE of WT and GNAQQ209L mice, with a significantly smaller percentage in GNAQQ209L. (Each point represents % from one mouse, mean ± SEM; unpaired t test). (C) Fraction of surviving WT, GNAQQ209L, and BrafV600E FACS sorted melanocytes plated on fibronectin (each line represents an independently derived primary culture, two-way ANOVA). (D) Representative images of melanocyte morphology 2 days post-plating on fibronectin-coated wells, showing increased dendrite formation in GNAQQ209L melanocytes. (E) Time lapse microscopy of two WT melanocytes plated on fibronectin. The circled cell adopted a round shape shortly before being lost from view. (F) Time lapse microscopy of two GNAQQ209L melanocytes showing a dendritic cell morphology that remained stable over time. (G) Representative images of BRAFV600E melanocytes at 2 and 8 days post-plating on fibronectin. Scale bars represent 100 μm in D, 20 μm in E and F, and 50 μm in G. (H) Fraction of surviving WT and GNAQQ209L IFE melanocytes co-cultured with mouse embryonic fibroblasts (MEFs), showing initial growth above the baseline for both genotypes before loss began (each line represents an independently derived primary culture, two-way ANOVA). (I) Representative images of FACS sorted WT and GNAQQ209L IFE melanocytes co-cultured with MEFs. While the WT and GNAQQ209L IFE melanocytes had a similar spindle cell morphology at day 1, the GNAQQ209L melanocytes progressively developed large and abnormal shapes.