The abundance of protein has long intrigued researchers. With more than 20,000 protein molecules currently identified, researchers are racing to unravel their roles in human health and disease. To do this, researchers monitor protein activities inside a cell using a tag that produces light in nature. However, who would have thought that this light-producing tag is also a protein molecule termed as a bioluminescent? In a scoping review published in the March issue of the Journal of Young Investigators, Kwing Yeung Chan, Hugo Yat Hei Kwong, and Dei Men Szeto from the University of Hong Kong recount the chronicle of a specific bioluminescent from its discovery to its application.