Furthermore, these cells have increased exposure to the factors necessary for tumor relapse, including CXCL12, through its receptors CXCR4 and CXCR7 [25], IL6 through the Jak2/Stat3 pathway [26, 27], EGF, FGF and IGF [28, 29], among others. Here, CXCR4 is linked to neoplasm.