Reduced adhesionof BM-derived ADAP-, PFN1-, WASp-, and ARP2/3-deficient MKs on ECM proteins. (A) Cryosections of BM from control (Adap^fl/fl), ADAP-, PFN1-, WASp-, and ARP2/3-deficient mice stained for GPIX (cyan) to visualize MKs, and (pro)PLPs and CD105 (red) to identify sinusoids. The images from the bottom panel are magnified from the regions indicated in the upper panel. Scale bars represent 30 μm (upper panel) and 10 μm (lower panel). (Bi) Gating strategy for the detection of (pro)PLPs and MKs in BM samples based on the size and expression of αIIbβ3. Shown is the dot plot of a Pfn1^fl/fl-PF4-cre BM sample and the corresponding control (Pfn1^fl/fl). (Bii) Quantification of (pro)PLPs in the BM as percentage of the control mean. The percentage of (pro)PLPs in the BM was calculated and normalized to the mean of their respective control MKs. The controls are indicated by dashed lines. (Biii) Quantification of MKs in the BM as percentage of the control mean. The percentage of MKs in the BM was calculated and normalized against the mean of the respective control MKs. The controls are indicated by dashed line. Each data point represents a single mouse. N = 3-9. (C) Normalized adhesion assay of in vitro cultured BM-derived MKs from the respective controls, ADAP-, PFN1-, WASp-, and ARP2/3-deficient mice on Horm collagen (Ci), fibrinogen (Cii), and fibronectin (Ciii). The percentage of adherent mutant MKs after 3.5 hours incubation was calculated and normalized against the mean of their respective control MKs. Controls are indicated with a dashed line. Each dot represents a technical replicate. The experiment was performed at least twice.