ACTA1 and melanoma: Similarly, Endo180 is most strongly expressed by the S2 CAF subpopulation, characterised by expression of ECM components, in the melanoma single cell RNA-Seq dataset33 (Supplementary Fig. 1d) whilst FAP and αSMA display a broader distribution including expression on lymph node fibroblasts, together indicating that Endo180 expression is associated with a discrete population of CAFs in solid tumours.