NBEAL2, SEC22B, and membrane-associated proteins in human MKs. Primary human MKs stained for NBEAL2 (green), SEC22B (red), and 1 of the following: calnexin (synthetic ER; magenta) (A), P-selectin (α-granules/precursors; magenta) (B), or SERCA3 (cortical ER; magenta; bars = 10 μm) (C). (D) Colocalization analysis based on Pearson’s correlation coefficient for NBEAL2-calnexin (n = 21 cells), NBEAL2–P-selectin (n = 21 cells), NBEAL2-SEC22B (n = 62 cells), NBEAL2-SERCA3 (n = 21 cells), SEC22B-calnexin (n = 21 cells), SEC22B–P-selectin (n = 21 cells), and SEC22B-SERCA3 (n = 20 cells; bars = 95% confidence intervals) indicates strong overlap among NBEAL2, SEC22B and P-selectin, with NBEAL2 having a weak association with calnexin. Images obtained as described in Figure 1. Colocalization channel images are shown in supplemental Figure 1.