To further address the mechanism underlying upregulation of CXCR4 by BAG3, nascent RNA was isolated and real-time RT-PCR demonstrated that BAG3 overexpression did not alter nascent CXCR4 mRNA in breast cancer cells (Figure 5a), indicating that BAG3 promoted CXCR4 expression independent of transcription initiation. Here, BAG3 is linked to breast carcinoma.