 The volume and strength of an excitatory synapse is strongly correlated with the size of the post-synaptic density, PSD, which is composed of scaffold proteins like shank and sapap. These scaffolds interact with the HOMA protein, which is also present in the PSD. When HOMA forms a condensed structure with these scaffolds, it promotes the formation of actin bundles, which are important for spine growth and stability. This process is regulated by calcium, calmodulin kinase 2, CAMKII, or the presence of HOMA1A, an immediate early gene product.