Figure 5. Photobiomodulation enhances phagocytosis via the upregulation of MerTK and has an anti-oxidative effect. Phagocytosis has several steps: binding to integrin, ingestion, and degradation of POS. FAK is thought to be involved in binding to integrin, and MerTK is thought to be related to the uptake of POS. Oxidative stress impairs the functions of RPE cells, such as phagocytosis. Our findings suggest that photobiomodulation can have an anti-oxidative effect and can activate MerTK. POS: photoreceptor outer segments; RPE: retinal pigment epithelium; FAK: focal adhesion kinase; MerTK: Mer tyrosine kinase (the big red arrow indicates upregulation and the normal arrow indicates “binding to receptors”).