GPR68 and cancer: Fig 6E lists the most strongly correlated GPCRs for each cell type. For CAFs and cancer cells, these data appear in excellent agreement with prior experimental results. For example, GPR68/OGR1 is strongly associated with CAFs in our analysis, consistent with evidence that it is a novel functional receptor in PDAC-derived CAFs [13]. Similarly, epithelial-enriched GPCRs (Fig 6E) are expressed in cancer cells [21] and, as shown below, in cancer cell lines.