Constitutive coexpression of wild-type GPVI and α2 collagen receptors does not impair platelet production. The expression of α2 integrins and human GPVI on CD41⁺ platelet precursors (top) from irradiated host animals reconstituted with α2-deficient bone marrow cells that were exposed to empty vector (left), empty vector + α2-expressing vector (middle), and α2-expressing vector + hGPVI-expressing vector (right) is shown. The boxed population indicates the population of CD41⁺ cells that express both α2 and hGPVI surface receptors. Expression of α2 and GPVI in the circulating blood platelets (bottom) of the animals shown in top panel is shown. Note that the fraction of α2⁺;GPVI⁺ double platelets is similar to that of double-positive CD41⁺ precursors in the bone marrow.