Quantification of kindlin-3, talin-1, and integrin protein levels in platelets and PMNs. (A) Western blot of kindlin-3 and talin-1 from different blood cell lysates. GAPDH and actin served as loading controls. (B) Copy number counts of platelet proteins were estimated with intensity-based absolute quantification. (C) Schematic representation of the workflow for quantification of protein copy numbers in platelet lysates. Heavy-labeled protein standards with known concentration were spiked into platelet lysates, and peptide ratios were determined by mass spectrometry. (D) Mass spectrometry–based absolute quantification of the copy numbers of kindlin-3, talin-1, and β3 integrin in K3+/+, K3+/n, K3n/n, and K3n/− platelets (N = 3, 2, 2, 2). Values are given as median ± range. (E) Mass spectrometry–based absolute quantification of the copy numbers of kindlin-3, talin-1, and β2 integrin in wild-type PMNs (N = 3). Values are given as median ± range.