LRRFIP1 interactions in resting and activated human platelets imply a role in the regulation of the platelet cytoskeleton. (A) Western blotting with anti-LRRFIP1 identifies a 160-kDa protein in platelets and the megakaryocytic cell lines, Meg-01 and CHRF-288-11. (B) Tandem mass spectrometry analysis LRRFIP1 coimmunoprecipitation (co-IP) from resting and activated platelets identified novel and known protein-protein interactions (Table 2). Shown is a Cytoscape visualization of the LRRFIP1 protein-protein interaction network in platelets (Cytoscape Version 2.5). Node colors indicate interactions detected in resting only (green), activated only (red), or both resting and activated (yellow) platelets. LRRFIP1, which was detected in both resting and activated co-IPs; LRRFIP1 is shown centrally in blue. Node diameters indicate the number of peptide hits; a semiquantitative measure of protein abundance. (C) Western blotting of LRRFIP1 co-IPs with specific anti-Flightless 1 and anti-Drebrin antibodies confirmed these protein-protein interactions.