Model setups.

A, In Setup 1, we capture the cell-derived CXCL12 gradient along the red line formed in the presence of clusters of CXCL12-secreting cells and CXCR7+ cells to examine the characteristics of isoform-specific gradients. B, In Setup 2, we simulate a section of a tumor and calculate the blood-tissue and endothelial-tissue gradients. All variables shown in figure are detailed in Appendix 2. C, A cross-sectional slice of the grid used for Setup 2.