PTH2 and neoplasm: Notable findings include the following: enrichment for tumor ligand PTH2 interactions with stromal receptor PTH1R in metastatic lesions; enrichment for human R-spondin family proteins in stroma-to-tumor signaling; enrichment for tumor ligand EFNA2 interactions with stromal receptor EPHA6; enrichment for chemokine and interleukin stromal receptors interacting with stromal ligands.