Claspin interacts with USP7. (A) U2OS cells were transfected with indicated siRNAs for 72 h and analyzed by IB with the indicated antibodies. The functionality of the USP1 siRNA has been demonstrated previously (Huang et al., 2006). (B) Lysates of 293T cells transfected with indicated plasmids for 24 h were subjected to Myc IP followed by IB. (C) Lysates of 293T cells were subjected to IP with USP7 antibody or preimmune rabbit serum (IgG) followed by IB. (D) 293T cells were transfected with WT or CI forms of Myc-USP7, and processed as in B. The extra band in the USP7 CI lane corresponds to ubiquitylated USP7 (unpublished data).