He next tested peptidoglycan recognition protein 2 (Pglyrp2) knockout (KO) mice to test the hypothesis that PGRPs play a role in motor control and anxiety-like behavior, and showed that both Pglyrp2 KO male and female mice exhibited anxiety-like behavior and that prefrontal cortex exhibited altered expression of genes related to synaptic plasticities, such as a significant increase in the expression of α-synaptic nuclear protein levels were significantly increased (Arentsen et al., 2018). This evidence concerns the gene PGLYRP2 and Anxiety.