FIG. 1.
Expression of tagged RARs in MEFs and ES cells. (A) Schematic representation of RAR with a C-terminal 3×Flag-HA tag and Western blot assay showing expression of tagged RARs in total extracts from cells expressing tagged RARα or RARγ or control cells (Tα, Tγ, and C, respectively). In the upper panel, tagged RARs were detected with anti-Flag antibody, and in the lower panels, endogenous and tagged RARs were detected with isotype-specific antibodies and endogenous RXR was detected with a pan-RXR antibody. (B) Phase-contrast microscopy after 5 days of culture in 10% or 0% serum showing that RA treatment of Taf4lox/− MEFs expressing tagged RARγ leads to serum-independent growth. (C) ChIP-qPCR on the Crabp2 RARE and the Prm1 promoter in cells expressing tagged RARα and control cells treated for 2 h with RA. The antibodies used are shown below the graph. The value obtained with each antibody and the control cells was assigned a value of 1, and fold enrichment relative to this value is indicated. GFP, green fluorescent protein.