PVT1 and breast cancer: To examine whether PVT1 regulates BC cell proliferation and metastasis by binding UPF1, we transfected Hs578t cells with si-PVT1#3, sh-UPF1#2 (sh-UPF1 #2 was the most efficient in knocking down UPF1 expression in Hs578t and MCF-7 cells, see Additional file 1: Figure B), or both, and evaluated the malignant phenotypes.