ITGA2 and Thrombocytopenia: Systemic murine Itga2 knockouts did not result in thrombocytopenia [9], [10], which was interpreted to mean that α2β1 is not involved in MK and proplatelet formation, in contrast to the wealth of data from other laboratories showing that in the bone marrow niche, the binding of MK α2β1 to type I collagen and subsequent activation of the Rho-ROCK pathway delays proplatelet formation [6], [7], [8].