EHT 1864 is a effective Rac family GTPase inhibitor for Rac1/Rac1b/Rac2/Rac3 (Kd: 40/50/60/250 nM).

EHT 1864 selectively inhibits Rac-induced lamellipodia formation, and specifically reverses cell transformation induced by constitutively activated mutants of Rac1 and Tiam1. EHT 1864 strongly impaires oncogenic Ras-induced cell proliferation in NIH 3T3 cells stably expressing H-Ras(61L) protein. [1] EHT 1864 also reduces both extracellular and intracellular levels of Aβ peptides by inhibiting the γ-secretase-dependent cleavage of APP. [2] In cultured hippocampal pyramidal neurons, EHT 1864, via inhibition of Rac1, rescues the phenotype induced by Rich2 knock-down. [3]

EHT 1864 (40 mg/kg i.p.) significantly reduces Abeta 40 and Abeta 42 levels in guinea pig brains. [2]

Inhibitor:GTPase binding analyses: For inhibitor:GTPase binding analyses, aliquots of small GTPase solution (containing 1 μM inhibitor) are titrated into a solution of 1 μM inhibitor in the cuvette. Changes in fluorescence anisotropy are monitored at λex = 360 nm, λem = 440 nm, 30 s after each addition. All data analysis and curve fitting were performed using Microsoft Excel and QuantumSoft's ProFit for Mac OS X.

NIH 3T3 cells stably expressing oncogenic Ras are plated in 96-well plates. The cells are cultured for up to 4 days in complete growth medium, either alone, or supplemented with 5 μM EHT 1864. Cell growth is then assessed using the conversion of MTT to a formazan product. Briefly, the MTT reagent (from a 5 mg/ml solution diluted in PBS) is added to the wells at a final concentration of 0.5 mg/ml, and the cells are further incubated for 4 h at 37°C. The medium is then removed, and the reaction is terminated by adding 100 μl/well Me2SO. The absorbance is read at 570 nm using a microplate reader.(Only for Reference)