Aberrant collagen and convulxin-induced aggregation in GP VI^null mice. Blood was withdrawn from GP VI^WT, GP VI^het, and GP VI^null mice. Mouse platelet-rich plasma was obtained by pooling blood from animals with the same genotype. The platelet number in each sample was normalized to 240 × 10⁹/L with platelet-poor plasma. Indicated concentrations of acid-insoluble fibrillar collagen (type I), convulxin, and PMA were added to stirred platelets and the aggregation profiles are presented.