Fig. 2. Forced expression of a dominant-negative Meis interferes with RPC proliferation. (A-C) MeisEnR-transfected chick eyes are microphthalmic. (D-E') BrdU incorporation following ectopic expression of GFP (D,D') or MeisEnR together with GFP (E,E'). (F) Quantification of the results from D-E'. Error bars indicate s.d. (G,H) TUNEL labeling of HH16 retinae transfected with nuclear red fluorescent protein (nRFP; G) or MeisEnR together with nRFP (H). (I) TUNEL labeling on a HH16 chick retina treated with DNase I to visualize the effectiveness of the labeling strategy. (J-L) Clonal analysis. Representative clones infected with RIS(B)-GFP (J), RIS(B)-Meis2 (K) and RIS(B)-MeisEnR (L) visualized with the virus-specific antibody p27 (green). RIS(B)-MeisEnR-infected cells express the Myc-tag C-terminally fused to EnR (red, L). (M) Number of cells per clone and per section plotted as a function of the frequency at which clones of the respective sizes were observed.