Caskin1 is recruited to EphB1 tyrosine kinase via Nck. (a) COS7 cells were transiently transfected with HA-EphB1 or/and V5-Caskin1, cell lysates were then subjected to immunoprecipitation with anti-V5 antibody. Bound proteins were separated by SDS-PAGE, transferred to nitrocellulose, and probed with anti-HA and anti-Nck antibodies. (b) Biotinylated tyrosine phosphopeptides were synthesized (Y594-P, Y751-P, and Y1009-P as negative control) and immobilized on streptavidin-beads as described in the Methods. These phosphopeptides were incubated with rat brain lysates. Precipitated proteins were resolved by SDS-PAGE, transferred to nitrocellulose and analyzed by anti-Caskin1 and anti-Nck antibodies.