FIGURE 1.

Timeline of circular RNA. (A) The concept of circRNAs was proposed in 1976. Extensive research on circRNAs began in 2012 with the discovery of large amounts of circRNAs in human cells. These researches have improved yields of circRNAs, realized the synthesis of large circRNA molecules, and expanded the applications of circRNAs. (B) Times cited and publications over time. There were a few publications about circRNAs before 2012. Since the discovery of large amounts of circRNAs in human cells in 2012, the number of publications and citations has increased year by year and is still rising.