SDC4 and neoplasm: We performed a clinical relevance analysis on the representative ligand-receptor pairs in the PAAD data from TCGA and found that the ligand-receptor pairs represented by ADGRE5-CD55, AGRN-DAG1, EFNA1-EPHA2, COL1A1-CD44, THBS1-SDC4, and LGALS9-CD44 were expressed at a higher level in tumor tissues compared with normal tissues, and the high expression of ligand-receptor pairs was associated with poor prognosis (Figures 3B and S9–S11).