Fig. 3. ChIP analyses reveal the association of proteins methylated on arginine residues with the transcription start site region of the cyclin E1 promoter in vivo. (A) Crosslinked chromatin from G₀-arrested NIH 3T3 fibroblasts was immunoprecipitated with an anti-methylarginine monoclonal antibody or a control antibody (anti-Flag epitope). One-tenth of the input chromatin and the immunoprecipitated chromatin were analysed by quantitative PCR for the presence of mouse cyclin E1 promoter fragments CE12 or CE6, or for fragments corresponding to the mouse albumin gene (Alb). (B) ChIPs performed as in (A) but using an antiserum directed against methylated histone H4 (me-R3-H4).