CD9 (Tspan4) and CD81 (Tspan28), depending on tumor type, can promote or suppress disease progression [25,26,27,28], while some other Tspan proteins, such as CD82 (Tspan27) and CD63 (Tspan30), have solely been established as tumor suppressors [29,30,31,32]. The gene discussed is TSPAN18; the disease is neoplasm.