PAM for RNA-Guided Cas9 (image) DOE/Lawrence Berkeley National Laboratory Caption Short DNA sequences known as "PAM" (shown in yellow) enable the bacterial enzyme Cas9 to identify and degrade foreign DNA, as well as induce site-specific genetic changes in animal and plant cells. The presence of PAM is also required to activate the Cas9 enzyme. Credit Illustration by KC Roeyer Usage Restrictions credit to KC Roeyer Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.