FIG 4.

PRMT4 interacts with pRb and is primarily responsible for pRb arginine methylation in vivo. (A) HEK293T cells were cotransfected with an HA-tagged empty vector or individual HA-tagged PRMTs with Flag-pRb expression plasmids. Five hundred micrograms of each cell lysate was immunoprecipitated (IP) with 3 μg of anti-pRb R787-Me2 overnight, and methylated Flag-pRb was detected using an anti-pRb monoclonal antibody. (B) Immunoprecipitation with either anti-mouse IgG or anti-Flag antibody M2 from cell lysates prepared from isogenic U2OS cells expressing Flag-pRb (WT). Interaction with PRMT4 was detected using an anti-PRMT4 antibody.