L1CAM and pleuropulmonary blastoma: FGF and its four FGFRs (FGFR1-4) regulate a multitude of cellular processes including cell growth, differentiation, migration and survival, and have been implicated in a number of physiological and pathological processes including angiogenesis, wound healing and cancer27,28 Interestingly, FGFRs can also be activated by non FGF ligands such as the cell adhesion molecules L1, NCAM129, which was also overexpressed in our PDX PPB model.