Single-cell RNA-sequencing dissection of human ccRCC tumours revealed that a population of tumour-associated macrophages (TAM) that express TREM2, APOE and C1Q genes is associated with recurrence after surgery13 and that a similar population of TAM2-like cells is enriched in late stage and metastatic tumours versus early stage tumours14, implicating TAMs in processes associated with aggressive ccRCC disease. The gene discussed is APOE; the disease is nonpapillary renal cell carcinoma.