As components of the coronavirus RTC, cell proteins can also modulate sgmRNA ratios. Infectious bronchitis virus (IBV) N protein  was recently shown to recruit  cellular helicase DDX1 to viral RTCs, facilitating TRS read-through and synthesis of long sgmRNAs. Interestingly, DDX1 recruitment requires N protein phosphorylation by cellular GSK3 kinase. Thus, the cell factor DDX1, attracted by phosphorilated N protein, provides a unique strategy for the transition from discontinuous to continuous transcription in coronaviruses to ensure balanced sgmRNA and full-length gRNA synthesis.