CXCR4 and renal cell carcinoma: Wang et al. (2012b) developed recombinant CXCR4-RNAi plasmids that they transfected into RCC A-498 cells overexpressing CXCR4 in vitro. Specific downregulation of CXCR4 by RNAi inhibited cell growth, invasion, and migration and induced cell apoptosis in RCC in vitro (Wang et al., 2012b).