Embryonic suppression of terminal differentiation in vivo and in vitro upon loss of AP-2s. (A) Histology and immunofluorescence of the epidermis from E17.5 γ-cKO, DcKO, and WT skins. Note parakeratosis in DcKO epidermis (arrows). Bars, 20 μm. (B and E) Real-time PCR on mRNAs from embryonic epidermis and cultured 1°MKs. DcKO and α-cKO levels are expressed as fold changes versus WT (set to 1). Error bars represent standard deviation for three or more independent experiments. Cultures were in 50 μM Ca²⁺ (differentiation-restricted) media. (C) α6 BrdU FACS was performed on cells from epidermis of E18.5 mice pulsed 4 h with BrdU before analyses. Asterisk denotes significant difference (P < 0.05) by Student's t test. (D) Anti-active caspase 3 staining and quantification. Total number of cells counted in E18.5 epidermis are shown along with number of cells scoring positive for Cas3. (F) At 0 h, 1.5 mM Ca²⁺ was added to induce terminal differentiation. mRNAs were isolated at indicated time points and real-time PCR was performed. Lor, loricrin; Fil, filaggrin.