Squarunkin A hydrochloride is a potent and selective UNC119-cargo interaction inhibitor. Squarunkin A hydrochloride selectively inhibits the binding of a myristoylated peptide representing the N-terminus of Src kinase to UNC119A with an IC50 value of 10 nm. Squarunkin A hydrochloride interferes with the activation of Src kinase in cells [1].

Squarunkin A (2.5 μM, 0.625 μM, 0.078 μM, and 0.01 μM) treatment results in a concentration-dependent reduction of Src phosphorylation [1]. Squarunkin A does not target the lipoprotein-binding sites of other lipoprotein chaperones, such as PDE6d, AIPL1, and RhoGDI, which bind S-prenylated proteins. Squarunkin A binds to UNC119 in cell lysate and interferes with Src activation [1].