We’ve mentioned the $25 million-plus that a handful of pesticide and processed food companies have poured in to opposing the GMO labeling bill that will be up for vote in California this November. And that opposition is only logical; although Prop 37 technically only applies to California, odds are good that, if it passes, it will have implications for the entire food industry in this country.

Now, we thought we’d highlight a few of the celebrities who have been speaking up for GMO labeling. Have you seen others? Let us know in the comments section below.

In an interview on the Rodale website, musician Jack Johnson described his involvement in the cause. Here’s a clip:

According to the five-mile-long endorsements page on the pro-labeling California Right to Know website, a group including Roseanne Barr, Chevy Chase, Maroon 5, and Daryl Hannah has also officially signed on with the campaign.