MS4A1 and urinary bladder carcinoma: HE staining of the P1 sample revealed abundant TLS presence (Figure 3A), and spatial gene expression analysis identified this sample as belonging to the luminal subtype (Figure 3B), where KRT19 was used as a marker for bladder cancer, KRT20 for the luminal subtype, KRT5 and KRT14 for the basal subtype,[16] COL1A1 served as a marker for fibroblasts, PECAM1 for endothelial cells, CD20 for B cells, and CD3 for T cells.