Figure 1. Live imaging of cultured keratinocytes.

a: Size distribution of live imaged (n=81) and non imaged control (n=1487) colonies after 7 days culture, in 3 independent experiments. Box boundaries indicate the 25^th and 75^th percentiles. Line across box is the median. Whiskers indicate 1^st and 99^th percentiles. There is no statistically significant difference between the distributions (p=0.15 Kolmogorov-Smirnov test). b: Typical colonies cultured for 6 days, treated with EdU and fixed 24 hours later,. White, differentiation marker KRT1; yellow, EdU; green, keratinocyte marker KRT14; blue, DAPI. Images representative of 3 independent experiments. Scale bar 100μm. c: Cycle times of 2127 live imaged cells from 3 independent experiments, median 15.7 hours, 99% of all divisions occur within 48 hours. d,e: Representative examples of two types of lineage trees, expanding, d, and balanced e, from 3 independent experiments. Dividing cells are green, non-dividing cells magenta and cells observed for <48 hours grey. See Figure 2a,b and Supplementary Table 1 for complete data set and Supplementary Videos 1 and 2 for example videos. f,g: Division outcomes in expanding (f, 928 divisions) and balanced colonies (g, 930 divisions), expressed as percentages with 95% confidence intervals. h Cell cycle time distributions in balanced and expanding colonies Box boundaries indicate the 25^th and 75^th percentiles. Line across box is the median. Whiskers indicate 1^st and 99^th percentiles. i The length of the preceding (maternal) cell cycle for daughter cells with each division outcome. Box boundaries indicate the 25^th and 75^th percentiles, line across box is the median. Whiskers indicate 1^st and 99^th percentiles. There is no significant difference between cycle time distributions for any division outcome (P=0.18 Kruskal-Wallis Test, n=1109 divisions for PP, 338 PD and 330 DD).