It has been reported that miR-335 suppresses breast cancer metastasis by targeting SOX4 and Tenascin C [24], small cell lung cancer metastasis by targeting IGF1R and RANKL [25], and induces apoptosis of breast cancer cells by regulating ERα, IGF1R, SP1, and ID4 [26]. The gene discussed is ID4; the disease is small cell lung carcinoma.