The phrase "key precursor" refers to something that comes before or leads to important or significant developments. It plays a major role in setting the stage for future events or shaping their outcome. Full definition
And yet Best Picture has remained elusive, even in the era of the expanded lineup, which Moonrise failed to crack despite scoring nominations from key precursors such as the Producers Guild of America (PGA), Writers Guild (WGA) and Golden Globes. (awardswatch.com)
A typical 3.5 horsepower gas mower, for instance, can emit the same amount of VOCs — key precursors to smog — in an hour as a new car driven 340 miles, say industry experts. (crunchydomesticgoddess.com)
It could help in digestion, he speculates, or be a key precursor for other metabolically important chemicals, such as prostaglandins. (sciencemag.org)