Class 3 semaphorins are secreted molecules that interact with plexin transmembrane receptors to regulate axon guidance, with additional roles in cell migration, vascular and lymphatic development, tumor growth and suppression, and immunologic response.77, 78, 79, 80 BCL11A transcriptionally represses the semaphorin Sema3c in radially migrating neurons during embryonic cortical development.16 The gene discussed is BCL11A; the disease is neoplasm.