Description_x000D_ Packaging_x000D_ 5, 25 mg in glass bottle_x000D_ Biochem/physiol Actions_x000D_ RRD-251 hydrochloride is a reversible, potent, and selective disruptor of Rb/Raf-1 interaction. The retinoblastoma tumor suppressor protein (Rb) controls the G1-S boundary by repressing the transcriptional activity of the E2F family of transcription factors. Raf-1 kinase binds and phosphorylates Rb early in the G1 phase. RRD-251 significantly inhibits angiogenesis and tumor growth in vivo in an Rb-dependent manner. RRD-251 does not inhibit the binding of B-Raf to Rb and Raf-1 to Mek1/2. Also, RRD-251 does not affect the kinase activities associated with cyclin D, cyclin E, or Raf-1.