However, the downregulation of both CX3CL1 and CX3CR1 when cultured in M2 macrophage-conditioned medium supports the dual functional role of CX3CL1. This discrepancy may be attributed to the dual role of CX3CL1 acting both as a chemoattractant for leukocytes as well as an adhesion molecule for the tumor cells. This evidence concerns the gene CX3CR1 and neoplasm.