Although exhaustive studies aimed at identifying the downstream targets of SOX4 have been performed on the genome- and transcriptome-wide levels in various types of cells, such as human mammary epithelial cell line (HMLE) [23], embryonic neural stem cells [24], small cell lung cancer cells [25], acute lymphoblastic leukemia cells [26], the SOX4-induced proteome changes, especially in human CSCs, have not been investigated, which would be important for the investigation of the mechanisms underlying SOX4-driven cancer stemness and development of a novel strategy of SOX4 inhibition. The gene discussed is SOX4; the disease is small cell lung carcinoma.