CX3CL1 and neoplasm: Therefore, the coupling of CX3CL1-directed cellular interactions and the ICAM-1/LFA-1-mediated feedback loop between circulating NSCLC cells and VBMECs constituted a vicious cycle to recruit more CTCs, eliciting higher vertebral microvascular endothelial permeability and increasing the aggressiveness of tumor cells, which facilitated spinal metastasis of circulating NSCLC cells.