Actin Cytoskeleton (image) University of Pennsylvania Share Print E-Mail Caption Actin is an abundant protein, present in every cell. Penn Vet researchers showed that differences in the order of nucleotides -- not the amino acids -- governed the distinct functions of two forms of actin. Credit University of Pennsylvania Usage Restrictions In context of reporting Share Print E-Mail 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.