CSE1L and osteosarcoma: In melanogenesis, CSE1L links and regulates cAMP/PKA and Ras/ERK signal pathways to induce CREB and MITF expression.28 In another study, the CSE1L protein was found to interact with mutS homolog 6 (MSH6) and positively regulate the MSH6 protein to promote osteosarcoma progression.29 CSE1L, also as a microvesicle membrane protein, can be detected in tumour‐derived exosomes/microvesicles.10 Because tumour cells secrete exosomes/microvesicles more frequently than do normal cells, CSE1L can be used as a diagnostic marker for tumours.30