CXCR4 and neoplasm: The association between BM and mutation in PIK3CA and BRAF, expression of NCAM, EGFR, and CXCR4, MGMT methylation and increase in the tumor marker CA19.9 have also been investigated, but only in one or two studies each and on small samples, so the possible predictive potential is hard to determine [11, 16, 26, 29, 31, 44, 59, 64].