ACTA2 and cancer: Strong correlations were observed between H&E digital stroma scores and a number of previously established transcriptional signatures, including StromalScore using ESTIMATE,17 cancer-associated fibroblast (CAF) score from Isella et al18 and fibroblast score from MCPcounter,19 alongside individual CAF markers ACTA2 (alpha-smooth muscle actin; αSMA) and FAP (figure 1B, C).