Fig. 1. Characterization of anti-Cdt1 antibodies. (A) 10 µg of protein extracts prepared from U2OS cells transiently transfected with either empty vector (lanes 1,3) or with plasmid expressing hCdt1 (lanes 2,4) were probed with anti-Cdt1 serum in the absence (lanes 1,2) or presence of competitor peptide (lanes 3,4). (B) 50 µg of protein extracts obtained from NHDF were blotted with anti-Cdt1 serum in the absence (lane 1) or presence (lane 2) of competitor peptide. The arrow indicates hCdt1 protein. (C) 50 µg of protein extracts from U2OS cells transfected with Cdt1-expressing plasmid (lanes 1,4), or from U20S (lanes 2,5) or HeLa (lanes 3,6) cells probed with immunopurified anti-Cdt1 antibodies in the absence (lanes 1-3) or in presence of competitor peptide (lanes 4-6).