FAP and neoplasm: In particular, by using six CAF markers (CD29, FSP1, FAP, αSMA, PDGFRβ and Caveolin1), the authors show that S1-CAFs are associated with an immunosuppressive tumor microenvironment by attracting T cells and promoting their differentiation into T-reg, in contrast to S4-CAFs that are associated with high CD8+ T cell infiltration.