Histologically, the distribution of fibroblasts (or stromal cells) in the tumors varied, and we observed that, in general, post-NACT tumors displayed more regions with fibroblasts infiltrations (PDGFRβ+) among cancer cell areas than in treatment-naïve samples, which were more homogenous (Fig. 4b, Suppl. The gene discussed is PDGFRB; the disease is cancer.