Presence of FANCD2 rescues TRF1 from PARsylation by impairing TNKS1-TRF1 complex formation. (A) Immunoprecipitation of PD20 or PD20cor cell extracts with TRF1 (A,D) or TNKS1(B) antibodies or non-immune control (β-actin) were performed as in Materials and Methods and corresponding immunopellets were resolved on 4-12%SDS PAGE followed by Western blotting and probing with TNKS1 (A) or TRF1 antibodies (B). FANCD2 levels in the same cell extracts is shown on Western blot (C). In parallel, immunoblots with TRF1 immunopellets were probed with anti-PAR antibodies (D). Corresponding signals of TNKS1, TRF1 or PAR-TRF1 proteins were digitized from the scanned blots and the relative percentages were included on the right side of each immunoblot panel as bar diagrams.