To determine if DDR2-regulated arginase-1 activity in CAFs impacted tumor cell colonization in vivo, we co-injected WT mice intraperitoneally with syngeneic luciferase-positive KPCA tumor cells (low DDR2 expression and low arginase activity) (Supplementary Fig. S1A, Supplementary Fig. S5A) +/− various luciferase-negative mouse omental CAF cell lines from WT or Ddr2−/− mice. Here, ARG1 is linked to neoplasm.