IRAK-1-4 Inhibitor I is a dual inhibitor of IRAK4 and IRAK1.

IRAK-1-4 Inhibitor I has IC50 greater than the highest concentration tested (10 μM) against a panel of 27 other kinases, including the most closely homologous (outside of the IRAK family) Lck and pp60SRC. Additionally, IRAK-1-4 Inhibitor I does not show any signs of cytotoxicity in a 72 h proliferation assay in HeLa cells (ED50>30 μM). Significant inhibition of IRAK-1 is observed with IRAK-1-4 Inhibitor I (IRAK-1 IC50=0.3 μM)[1]. IRAK-1/4 inhibitor eliminates the LPS-induced increases in Bcl10, NF-κB, and IL-8. IRAK-1/4 mediates LPS-induced IL-8 activation and functions upstream of Bcl10. The LPS-induced increase in Bcl10 declines by 73% (from 5.18±0.22 to 2.36±0.08 ng/mL), and the IL-8 response decline by 60% (from 2.64±0.31 to 1.14±0.08 ng/mL)[2].

Kinase Assays: Cell-free kinase assays are done in quadruplicate with 1 μM ATP to determine the IC50 values of AV-951 against a variety of recombinant receptor and nonreceptor tyrosine kinases including VEGFR1, VEGFR2, VEGFR3, c-Kit, PDGFRβ, Flt-3 and FGFR1.

IRAK-1-4 Inhibitor I is dissolved in DMSO and stored, and then diluted with appropriate media before use[2]. NCM460 cells, grown in 24-well plates, are incubated with 50 μM IRAK-1/4 inhibitor for 2 h. After 2 h, the media are changed, and new media with or without LPS (10 ng/mL) added. Treatment is terminated at 6 h, and spent media and cells are collected for IL-8 and other assays[2].