UBAP2L is a novel BMI1-interacting protein. (A) Strategy for large-scale purification of BMI1-containing protein complexes using a Tet-On system to induce expression of BMI1-PC-Flag. *The clone used to perform complex purification. (B) Proteins identified by MS in eluates from Flag-resin following complex purification. PcG proteins are in bold. Three independent experiments were performed and results from a representative experiment are shown. Proteins identified with a minimum of 2 unique peptides and present in at least 2 of the 3 experiments were included in the table (false discovery rate <1%). UBAP2L was found in all 3 experiments. (C) Immunoprecipitations performed using extracts from HEK 293 control or Flag-UBAP2L–expressing cells. The antibodies used to perform the immunoprecipitations (top right) and the immunoblottings (bottom right) are indicated. *The position of full-length UBAP2L protein.