For GPCR dimerization purposes, Luker et al. [98] (2009) applied the FLuc-based PCA (NFLuc-416 and CFLuc-398) to investigate the homo- and heterodimerization of CXCR4 and CXCR7 in a tumor xenograft model of breast cancer. Here, CXCR4 is linked to breast cancer.