It’s official—there are some 42 million protein molecules in a simple cell, revealed a team of researchers led by Grant Brown, a biochemistry professor in the University of Toronto’s Donnelly Centre for Cellular and Biomolecular Research. Analyzing data from almost two dozen large studies of protein abundance in yeast cells, the team was able to produce for the first time reliable estimates for the number of molecules for each protein, as revealed in a study published this week in the journal Cell Systems.