Fig. 2. In vivo association of Ring1B with mammalian PcG proteins. (A) Specific co-immunoprecipitation of Ring1B from 11.5 dpc mouse embryos using antibodies against Mel18 and Rae28/Mph1. The signals corresponding to the immunoglobulin heavy chains are indicated by arrowheads (Ig). (B-F) Comparative analysis of the subnuclear distributions of endogenous RING1B and MEL18 (B), BMI1 (C), RING1A (D), RAE28/MPH1 (E) and exogenous Mph2 (F) in normal or transfected human osteosarcoma U2-OS cells using indirect immunofluorescence. (Parts a) The signal of RING1B (green). (Parts b) The signals of endogenous MEL18 (B), BMI1 (C), RING1A (D), RAE28/MPH1 (E) and exogenous Mph2 (F) (red). (Parts c) Merged images. (Parts d) Phase contrast views. Monoclonal and polyclonal antibodies are indicated as M and P, respectively, in parentheses.