CCL21 and cancer: These cell clusters include tumor cells (MLANA+, MITF+, and PRAME+), T cells (CCL5+, CXCR4+, CD8A+), NK cells (NKG7+, GNLY+, GZMB+), B/Plasma cells (IGL3-1+, IGLV2-14+, IGLV1-40+), myeloid cells (C1QB+, C1QC+ and CD74+), cancer-associated fibroblasts (CAF, MGP+, RGS5+, COL1A1+), and very small fractions of other cell types: endothelial cells (PECAM1+, RAMP2+ and CCL21+) and photoreceptor cells (RCVRN+) (Fig. 1a–c).