C3 and cancer: Several scRNA-seq analyses have elucidated fibroblast heterogeneity in some cancer types.[12,24,44] MyCAFs and iCAFs were revealed to have distinct morphologies and spatial distribution in breast cancer.[24] In pancreatic ductal adenocarcinoma, Chen et al[44] detected complement-secreting CAFs expressing high levels of C3, C7, CFD, and CFH, which might modulate the immune and inflammation response.