We considered that tumor cells invading the lung may elicit an immune response as seen (Fig 2I); therefore, we used qRT–PCR to determine expression of Cd8, Ifnγ, and Gzmb that was indeed seen in PBS conditions, however with lower levels upon CXCR4 inhibition potentially reflecting less tumor cells in the lungs (Fig 6J–L). Here, CXCR4 is linked to neoplasm.