On the other hand, cancer cell invasion and metastasis are highly linked with the presence of filopodia.39 In breast cancer, increased formation of filopodia was found to strengthen the migration of cells, and cell migration in vitro and metastasis in vivo were suppressed by the inhibition of filopodium formation.30, 31 We observed that filopodium formation in lung cancer cells was inhibited by CBX4 knockdown, suggesting the attenuation of metastatic abilities (Figure 5F). Here, CBX4 is linked to lung cancer.