Signaling properties of ROR1 in RS cells and targeting with UC-961 antibody. (A) Pull-down (P.d.) assays were performed to study the activation of Rac1 and RhoA in the presence/absence of Wnt5a in the RS-PDX models. (B) Chemotaxis of RS1316 and IP867/17 PDX-derived cells in response to CXCL12 or CCL19 chemokines, used alone or in the presence of Wnt5a (≥3 independent experiments). Data are reported as percentage of migrated cells, calculated as number of migrated cells over the total number of cells seeded in the upper chamber of the Boyden chamber. Statistical analysis was performed using the Mann-Whitney test. Box plots show the distribution of values: median, interquartile range, minimum and maximum values. *P < .05; ***P < .001. (C) ROR1 targeting with UC-961 antibody, which prevents the binding of Wnt5a to ROR1, in a subcutaneous model of RS-PDX. Tumor volume (day 47; left panel) and growth kinetics (right panel) are depicted. Arrows indicate treatment (Tx) administration. Mean and standard deviation are displayed in both graphs. Statistical analysis was performed using the Mann-Whitney test; results were nonsignificant. GTP, guanosine triphosphate; IB, immunoblot; NC, negative control; PC, positive control.