Mo. Rev. Stat. § 304.311
304.311 Observance of lane — direction — control signals.
304.311. Observance of lane — direction — control signals. — When lane-direction-control signals are placed over the individual lanes of a street or highway, vehicular traffic may travel in any lane over which a green signal is shown, but shall not enter or travel in any lane over which a red signal is shown.
(L. 1969 S.B. 180 § 5)