FGFR1 and neuroblastoma: In relapsed NB, the activating mutations of the RAS‐MAPK pathway detected include mutations in neurofibromatosis type I (NF1), v‐raf murine sarcoma viral oncogene homolog B1 (BRAF), tyrosine‐protein phosphatase nonreceptor type 11 (PTPN11), fibroblast growth factor receptor 1 (FGFR1), KRAS, NRAS, HRAS, and ALK.123, 129