Nucleolin binds to the four ErbB receptors.

<p>(A) COS7 cells were transiently co-transfected with expression vector of each of the ErbB receptors and Myc-Nucleolin. Cell lysates were separated into cytosolic (supernatant) and total membrane (pellet) fractions. The pellet fraction was subjected to immunoprecipitation with anti-Myc (nucleolin) or anti-HA (control) antibodies and immunoblotted with specific ErbBs antibodies. Total pellet and supernatant extracts are shown in the right lanes of each panel. (B) COS7 cells were transiently co-transfected with expression vector of ErbB1 and Myc-Nucleolin. Nuclear and non-nuclear cell extracts were immunoblotted with anti-ErbB1 antibodies. As control for the fractionation purity Blots were reacted with anti-PARP antibodies (as a nuclear marker) and anti-tubulin antibodies (as a cytosolic marker). (C) Cell lysates prepared from SKBR3 cells were subjected to immunoprecipitation with either anti-nucleolin or anti ErbB2 antibodies and immunoblotted with either anti- ErbB2 or anti-nucleolin antibodies as indicated, as a control total cell lysates are shown in the right lane of each panel.