BUB1 and posterior cortical atrophy: To further determine the role of circ_0004087 in regulating the DTX resistance of PCa cells, we constructed DTX-resistant PC-3 cells (PC-3-DR) (Fig. 8D), and found that both circ_0004087 and BUB1 were significantly upregulated in PC-3-DR (Fig. 8E and F).