UPF1 and infection: On the other hand, circRNAs can be degraded in four ways15: (i) circRNAs can be degraded by RNase L upon cellular infection with a double-stranded RNA (dsRNA) virus16; (ii) highly structured circRNAs can be undergo decay mediated by UPF1 and G3BP117; (iii) circRNAs can be degraded after being bound by microRNAs in an AGO2-dependent manner in unique situations18; and (iv) m6A-modified circRNAs can be degraded through an endoribonucleolytic cleavage pathway, that is, the YTHDF2-HRSP12-RNase P/MRP pathway19.