SMAD4 and ocular melanoma: The expression level of common Smad4 was significantly higher in the shDRG2‐OM group than the control‐OM group on day 7 and day 14 (day 7, p < 0.01; day 14, p < 0.05) and was significantly higher in the shDRG2‐GM than the control‐GM on day 3 and day 7 (p < 0.05).