Effect of G protein on platelet extravasation. The number of extravasated platelets (inside tumor parenchymal and outside blood vessels) into tumor nodules of tumor-bearing mice was determined by automatic whole-slide imaging and analysis. The effect of G protein deficiency in platelets was determined by comparing extravasated platelets in mice with platelet-specific Gi deficiency (Gi△/△) (A), G13 deficiency (G13△/△) (B), or Gq deficiency (Gq△/△) (C) with their corresponding littermates. One whole section was imaged and analyzed from each tumor nodule (1 tumor nodule from 3 mice per group). Data are mean ± standard deviation. A 2-tailed Student t test was used to determine statistical significance; P < .05 was considered significant.