Evidence suggesting a functional role of ROR1 in B-ALL came from an siRNA study that systematically knocked down all tyrosine kinases in a panel of primary leukemia cells; in a t(1;19) B-ALL case, ROR1 emerged as the only tyrosine kinase that, when targeted with siRNA, significantly decreased the ex vivo viability of primary B-ALL blasts [20]. Here, ROR1 is linked to precursor B-cell acute lymphoblastic leukemia.