For example, semaphorin 3B (SEMA3B) and 3F (SEMA3F) were initially identified as tumor suppressors in lung cancer, because small cell lung cancer is correlated with a deletion in the short arm of chromosome 3 (3p21) (Roche et al., 1996; Xiang et al., 1996). The gene discussed is SEMA3B; the disease is lung carcinoma.