ROR1 (Tyrosine-protein kinase transmembrane receptor ROR1) is a type I membrane protein. It is a receptor protein tyrosine kinase that modulates neurite growth in the central nervous system. The ROR-family receptor tyrosine kinases consist of two structurally related proteins, ROR1 and ROR2. These proteins are characterized by having intracellular tyrosine kinase domains, which are highly related to Trk-family kinases, e, Xenopus/Amphibian,tracellular Frizzled-like cysteine-rich domains (CRDs) and Kringle domains. The ROR family members are highly conserved among species, such as C. elegans, Drosophila, , Xenopus/Amphibian,enopus and mammals. ROR1 and ROR2 are both involved in organogenesis with particular emphasis in neuronal differentiation. Increased e, Xenopus/Amphibian,pression of ROR1 in acute lymphoblastic leukemias (ALLs) as well as chronic lymphocytic leukemias (CLLs) implicate this protein as a potential tool for targeted immunotherapy in these diseases.