Molecularly t(4;14) results in simultaneous overexpression of two genes located on 4p: the multiple myeloma SET domain (MMSET), which is a homologous of histone methyltransferase, and the fibroblast growth factor receptor 3 (FGFR3), which is an oncogenic receptor tyrosine kinase. This evidence concerns the gene FGFR3 and plasma cell myeloma.