FIG. 7.

FA Proteins and BLM do not function in the linear signaling pathway through monoubiquitination. (A) Immunoblotting analysis to show that the monoubiquitination of FANCD2 is normal in BS cells. Nuclear extracts prepared from the indicated lymphoblast cells were probed with a FANCD2 antibody (FANCD2-L and FANCD2-S represent ubiquitinated and nonubiquitinated forms of this protein, respectively). (B) Immunoblotting analysis to show that monoubiquitination is not detectable for BLM, Topo IIIα, and RPA after HeLa cells are treated with MMC. As a control, monoubiquitination of FANCD2 is strongly induced under such conditions.