FGFR1 and neoplasm: Consistent with our findings in tumour-derived cell lines, MMTV-Metmt;Trp53fl/+;Cre and Trp53fl/+;Cre mammary tumours with spindloid pathology showed stronger immunohistochemical staining for FGFR1 when compared to tumours with non-spindloid pathologies (Fig. 3c).