Rtf1 binds Cks1/Cdc28 in vivo. (A) Cells harboring Flag-tagged Cks1 and HA-tagged Rtf1 were lysed and immunoprecipitated (IP) using anti-Myc (as a negative control), anti-HA, or anti-Flag antibodies. Immunoprecipitates were analyzed by SDS-PAGE and Western blotting using the indicated antibodies. The middle image shows a short exposure, and the bottom blot shows a long exposure. (B) Cells harboring Flag-tagged Cks1 and Myc-tagged Rtf1 were lysed and immunoprecipitated using anti-HA (as a negative control), anti-Myc, or anti-Flag antibodies. Immunoprecipitates were analyzed by SDS-PAGE and Western blotting using the indicated antibodies. The middle blot shows a short exposure, and the bottom blot shows a long exposure. Note that Cks1-Flag runs immediately below the IgG light chain in immunoprecipitates.