APOE is highly expressed by TAM. A, IHC analysis of APOE in human benign pancreas and PDAC samples. Scale bars, 100 μm. B, Quantitation of positive APOE staining as a percentage of area in a 20× field of view. At least three fields of view were averaged per sample. Adjacent/normal pancreas, n = 3; hPDA, n = 4. Statistical significance was determined using two-tailed t test. C, IHC analysis of APOE in normal mouse pancreas and orthotopic KPC tumor. Scale bars, 100 μm. D, Quantitation of positive APOE staining as a percentage of area in a 20× field of view. Five fields of view were averaged per mouse. Control, n = 3; orthotopic tumor, n = 6. Statistical significance was determined using two-tailed t test. E, UMAP visualization of 9 identified populations in orthotopic KPC tumors (n = 2). F, Violin plot of normalized expression of Apoe in identified cell populations in orthotopic KPC tumors (n = 2). G, Coimmunofluorescence of orthotopic KPC tumor with single channels of APOE (green), F4/80 (red), αSMA (white), and merge to show APOE and F4/80 colocalization. Two examples of APOE and F4/80 colocalization are denoted by white arrowheads. Scale bars, 25 μm. H, Experimental design for bone marrow–derived macrophage polarization assay. I, qRT-PCR analysis of Apoe mRNA levels relative to Cyclophilin A in four macrophage conditions (M0, M1, M2, and TAM). Statistical significance was determined using one-way ANOVA with Tukey test for multiple correction.