Epibrassinolide (BP55) (EBR) is a biologically active compound of the brassinosteroids, is a natural brassinosteroid (BR) derivative, is a plant regulator with a similar structure to mammalian steroids.

Cells were seeded at 1*10^4 density per well in 96-well plates and exposed to various concentrations of EBR for 24 and 48 h. 10 ul 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) dye (5 mg/ml) ?was added to each well and cells were kept at 37 C for 4 h. The resulting formazan crystals were solubilized in 200 ul DMSO.?The density of the solubilized formazan was read at 570 nm spectrophotometrically.