BTRC and nasopharyngeal carcinoma: To test whether circPVT1 interferes with the E3 ubiquitin ligase function of β-TrCP to regulate its target proteins, the β-TrCP expression level was assessed in NPC cells after overexpressing or knockdown of circPVT1. The results showed that circPVT1 did not affect the expression of β-TrCP (Fig. S5A).