OPN3 and malignant colon neoplasm: Although further investigation is required to fully elucidate the molecular mechanism of blue LED irradiation, including phosphorylation, G‐protein function, cAMP signaling and their relationship with apoptosis, this study showed a novel mechanism of blue LED irradiation by Opn3 and we consider that Opn3 could be an important target of colon cancer in clinical settings.