While tumor-cell-specific gene signatures validated the previously described “classical” and “basal-like” subtypes, they described two additional subtypes that arose from low-tumor-burden samples with high stromal content: “stroma-activated” PDAC was characterized by high expression of ASMA, SPARC, and FAP [114], whereas “desmoplastic” PDAC was characterized by high expression of structural and vascularized stroma components [114]. This evidence concerns the gene ACTA1 and neoplasm.