CBFβ inhibitor is a small molecule which binds to CBFβ and inhibits its association with Runx1 [1].

Core binding factors (CBFs) are heterodimeric transcription factors containing a DNA-binding CBFα component (a RUNX protein) and an enhancer of binding, CBFβ. CBF dimers plays important roles in hematopoiesis and, when dysfunctional, in leukemia [2].The interaction of CBFβwith Runx2 has a critical role in bone development [3].

In vitro: The ELISA results have shown that CBFβ Inhibitor is very effective in inhibiting the CBFβ-Runx1 interaction with an IC50 of 3.2 μM. In the leukemia cell line ME-1 expressing CBFβ-SMMHC, CBFβ Inhibitor reduced cell proliferation dose-dependently. Treatment with CBFβ Inhibitor for 3 days showed an increase in apoptotic cells. Treatment with CBFβ Inhibitor for 14 days individually or with all-trans-retinoic acid (ATRA) resulted in cells with greater variation in size and shape, lower nuclear-to-cytoplasmic ratio, increased folding and lobation of nuclei, and more clumped chromatin. All of these morphology changes are consistent with differentiation to more mature forms. CBFβ Inhibitor at 50 μM increased proliferation of Hep-G2 cells. CBFβ treatment with Inhibitor resulted in a statistically significant reduction in Runx1 bound to DNA [1].

References:
[1].  Gorczynski M J, Grembecka J, Zhou Y, et al. Allosteric inhibition of the protein-protein interaction between the leukemia-associated proteins Runx1 and CBFβ[J]. Chemistry & biology, 2007, 14(10): 1186-1197.
[2].  Swiers G, De Bruijn M, Speck N A. Hematopoietic stem cell emergence in the conceptus and the role of Runx1[J]. The International journal of developmental biology, 2010, 54: 1151.
[3].  Kundu M, Javed A, Jeon J P, et al. Cbfβ interacts with Runx2 and has a critical role in bone development[J]. Nature genetics, 2002, 32(4): 639-644.