Inhibition of PCNA interactions by caPep and R9-caPep.

<p>a) The real-time SPR response curves were recorded for 1000 nM recombinant PCNA (rPCNA) flowing over the PIP-box sequence of FEN1 immobilized to the surface of a CM5 chip in the presence of 0 (red), 500 (blue), or 1000 (green) nM caPep. The dose-dependent binding of rPCNA to the immobilized FEN1 PIP-box sequence were also recorded under other rPCNA concentrations ranging between 250 and 1000 nM in the presence of 0, 500, or 1000 nM caPep (response curve not shown) and were used to calculate K_D of PCNA-FEN1 PIP-box interaction, as shown in the inserted table. SK-N-AS NB cells were treated with R9-caPep or R9-srbPep. Cells were fixed and immunostained with: b) mouse anti-FEN1 and goat anti-PCNA antibodies; c) mouse anti-LIGI and goat anti-PCNA antibodies; d) mouse anti-POLD3 and goat anti-PCNA antibodies. After DAPI counterstaining, nuclear co-localization of PCNA with FEN1, LIGI, or POLD3 was visualized by fluorescence confocal microscopy.