PLXNB2 and neoplasm: Finally, to determine the role of mouse Plxnb2 in CTC-immune cell cluster formation, we knocked down Plxnb2 gene expression in mouse 4T1 TNBC cells with siPlxnb2 transfections and found that loss of Plexin-B2 in tumor cells diminished the heterotypic 4T1-mouse WBC cluster formation (Fig. 6a–b).