Fig. 6. Hdac1 functions upstream of the interaction between cyclin D1 and p27. (A,B) cyclin D1 expression in wild-type (A) and add mutant (B) retinas. Almost all retinal cells express cyclin D1 in add mutants, while in wild-type retinas, cyclin D1 expression level decreases except in the CMZ (arrowheads). (C,D) p27b expression in wild-type (C) and add mutant (D) retinas. p27b expression is absent in the add mutant retinas. (E,F) add mutant retinas expressing Myc-tagged Xenopus p27 labeled with anti-Myc antibody (F, green) and anti-BrdU antibody (red). The introduction of Xenopus p27 inhibits BrdU incorporation in the add mutant retinas (arrowheads). (G,H) cmyc expression in wild-type (G) and add mutant retinas (H). cmyc is expressed in the peripheral CMZ (arrowheads) in wild-type retinas, while cmyc expression spreads centrally in add mutant retinas (arrows/lines). cmyc expression in wild-type retina treated with 1200 nM TSA (H, inset) spreads over a large region.