CREB1 and urinary bladder cancer: To investigate whether BCa-derived exosomal circRNA_0013936 regulates the expressions of FATP2 and RIPK3 in PMN-MDSCs via miR-320a/JAK2 and miR-301b-3p/CREB1 pathways, circRNA_0013936 knockout bladder cancer cells generated using CRISPR-Cas9 genome-editing system were kindly provided by Guanxin Wang (Sun Yat-sen University, Guangzhou, China).