RPK-1, bone morphogenetic protein receptor type-1B|ALK-6|BMP type-1B receptor|BMPR-1B|SKR6|activin receptor-like kinase 6|bone morphogenetic protein receptor, type IB|receptor protein kinase|serine/threonine-protein kinase receptor R6, Bone morphogenetic protein receptor type IB precursor, Serine/threonine-protein kinase receptor R6 (SKR6), Activin receptor-like kinase 6 (ALK-6), RPK-1