Western Blot Protein Expression Analysis

Western blotting experiments were performed by following a previous study [25 (link)]. The primary antibodies for CXCR4 (Enzo Life Sciences, Farmingdale, NY, USA), phospho-p53, STAT3, phosphor-ERK1/2, ERK1/2, phosphor-Rb (Cell Signaling Technology, Danver, MA, USA), p53, p21, phosphor-STAT3, Nibrin (NBS1), breast cancer type 1 susceptibility protein (BRCA1), checkpoint kinase 1 (Chk1), Chk2, Cyclin A (Santa Cruz, CA, USA), zonula occludens-1 (Zo-1), occludin (OCLN) (Thermo Scientific, Waltham, MT, USA), and Claudin-5 (MILLPORE, Damstadt, DE, USA) were used. The concentration of antibodies used was 1:1000 for primary antibodies and 1:2000 for secondary antibodies. After reacting with the antibody, the protein was observed by chemiluminescence using Amersham Imager 600 (GE Healthcare, Chicago, IL, USA); beta-actin was used as the loading control.