CXCR4 and neoplasm: In RMS, major characteristic of tumour aggressiveness is represented by the PAX3/7-FOXO1 fusion gene, a negative prognostic factor that regulates transcription of several downstream tumour-driving genes, including c-Met, CXCR4, FGFR4, IGFR-1R and PDGFRα kinases [14,15,16].