PVT1 and breast cancer: We and other researchers have also previously reported that Pygo2, a newly identified Wnt/β-catenin pathway component that was shown by the present data to be up-regulated by PVT1, activated MDR1 expression via the Wnt/β-catenin pathway, and inhibition of Pygo2 expression restored the chemotherapeutic drug sensitivity of human breast cancer and glioma cells [19, 26].