Similar to Gp1ba−/− platelets, 10aa−/− platelets exhibited not only lower basal P‐selectin (Figures 2A and S3A) and PS (Figures 2B and S3B) levels but also lower tumor cell‐induced P‐selectin (Figures 2C and S3C) and PS exposure (Figures 2D and S3D). Here, GP1BA is linked to neoplasm.