BCR and systemic mastocytosis: Although the dual BCR-ABL/SRC TKI dasatinib inhibits the kinase activity of KIT D816V in vitro (Shah et al. 2006; Lombardo et al. 2004) and has demonstrated efficacy in other myeloproliferative neoplasms, such as CML (Kantarjian et al. 2010), it has displayed minimal activity in patients with SM (Verstovsek et al. 2008).