UPP1 and neoplasm: Given our observations that fibronectin deposition in the lungs of tumour-bearing mice is reduced by Upp1 knockout, and that the UPP1 product, uracil, promotes fibroblast-mediated fibronectin deposition, it will be interesting to determine the extent to which UPP1-dependent immune landscapes and ECM deposition combine to generate the immunosuppressed environment necessary to foster metastatic seeding in the lung.