Similar fusions of COL1A1-PDGFB have been identified in two human STS subtypes: dermatofibrosarcoma protuberans (DFSP) and giant cell fibroblastoma; and increased expression of PDGFB is considered predictive of therapeutic response to PDFGR inhibitors14, although resistance subsequently develops27,28. Here, COL1A1 is linked to dermatofibrosarcoma protuberans.