Extended Data Fig. 3: MEKi injection temporarily inhibits ERK without promoting apoptosis or differentiation.
a, Representative two-photon time lapse frames of the wild type late growth hair follicles expressing the ERK biosensor 3 hours after intradermal injection of MEKi. Note that ERK activation began to emerge in the ORS (arrowheads) shortly after the time lapse started. b, Representative KrasG12D hair follicles treated with vehicle or MEKi in the whole mount skin stained for cleaved-Caspase3 (C-CASP3, red) and cell nuclei (DAPI, cyan). Apoptotic cell is indicated by arrowhead. c, Average numbers of apoptotic cells in the KrasG12D hair follicles treated with vehicle or MEKi. n = 3 mice (102 hair follicles from the skin treated with vehicle and 115 hair follicles from the skin treated with MEKi). ns, not significant, p = 0.1964. d, Representative images of the control and KrasG12D hair follicles stained for basal marker K14 or differentiation markers K75 and GATA3 (green). Cell nuclei were labelled by SiR-DNA or DAPI (magenta). Representative tissue deformations in the ORS are indicated by arrowheads. e, Representative images of the KrasG12D hair follicles after MEKi treatment stained for differentiation markers K75 and GATA3 (green). Cell nuclei were labelled by DAPI (magenta). Representative tissue deformations in the ORS are indicated by arrowheads. Border of the hair follicle is marked by white dashed lines in b, d and e. Two-sided unpaired t-test was used to calculate p values. Data are presented as mean ±S.D. with individual data points in c. Scale bars, 20 µm.
