Expression of enamel proteins in Col17−/− ameloblasts. A: mRNA expression of all of the enamel proteins examined (amelogenin, ameloblastin, enamelin, tuftelin, enamelysin, and DSPP) was down-regulated in ameloblasts of incisors of the Col17−/−mice in vivo. B: In vitro ameloblasts cultured from incisors of the Col17−/− mice showed down-regulated mRNA expression of amelogenin, ameloblastin and enamelin, although tuftelin expression was up-regulated relative to tuftelin expression of the cultured ameloblasts from the Col17+/+ mice. Neither enamelysis nor DSPP was expressed in ameloblasts cultured from the Col17+/+ and Col17−/− mice. C: Protein expression (FITC, green) of amelogenin and ameloblastin was decreased in ameloblasts cultured from the Col17−/− mice (D, F), relative to that in ameloblasts cultured from the Col17+/+ mice (C, E). (C, D) amelogenin staining; (E, F) ameloblastin staining; (C, E) cells from Col17+/+ mice; (D, F) cells from Col17−/− mice. Scale bar = 20 μm.