APOE and neoplasm: Among all six tumors that contained multiple tumor pROIs, we identified five proteins with a high CV (i.e., were among the proteins with the top 20% highest CV in all tumors), namely spectrin alpha chain, erythrocytic 1 (SPTA1), apolipoprotein E (APOE), band 3 anion transport protein (SLC4A1), fibronectin (FN1) and periostin (POSTN) (Figure S5a).