RR structures induced by inhibitors of CTP/GTP synthesis in live COS-7 cells are in a stable and stationary state in ≈ 70% of the cells. COS-7 cells were treated with ribavirin (A), DON (B), or MPA (C) for 24 h prior to microinjection with rabbit anti-IMPDH2 conjugated with Alexa 488 (green). After 10–15 min, sequential images (T1 to T5) were captured. Representative images from 2 min intervals for 10 min (A-C), or 6 min intervals for 30 minutes (D). No significant movement or relevant changes were observed in the size or shape of the cytoplasmic RR structures in most cells (71% out of 263 cells counted) during the observed time period of 10 min (n = 20) to 30 min (n = 5). Experiment was repeated independently 6 times in panel (A) and two times in panel (B) and (C). Nuclei were stained with Draq5 (red). Bars: 10 μm.