B-[(1R)-3-Methyl-1-[[(2S)-1-oxo-3-phenyl-2-[(2-pyrazinylcarbonyl)amino]propyl]amino]butyl]boronic Acid; [(1R)-3-Methyl-1-[[(2S)-1-oxo-3-phenyl-2-[(pyrazinylcarbonyl)amino]propyl]amino]butyl]boronic Acid; Velcade; Radiciol; Bortezomib Reference Standard, CAS No. ..179324-69-7