microtiter plate in an amount of 0 1 ml per well after the plate was incubated at 37 u00b0 c for 20 hours in a co 2 incubator 0 1 ml of a sample of uca1064 b appropriately diluted with medium a was added to each well the cells were further incubated at 37 u00b0 c for 72 hours in the co 2 incubator after the culture supernatant was removed the residue was washed once with physiological saline and then treated with 0 1 ml of methanol for 10 minutes to fix the cells the cells were stained with 0 1 ml of giemsa 39 s staining solution giemsa 39 s staining solution merck art 9204 merck amp co physiological saline 1 10 for 5 minutes after the staining solution was removed the residue was washed once with 0 2 ml of water then the dye was extracted with 0 2 ml of 0 1n hydrochloric acid and absorbance was measured at 620 nm with a microplate reader the concentration of the test compound at which the growth of the cells is inhibited by 50 ic 50 was calculated by comparing the absorbance of intact cells with those of the cells treated with the test compound at known concentrations table 2______________________________________ balb 3t3 h ras inhibitiontest compound activity ic sub 50 u03bcg ml ______________________________________uca1064 b 3 5______________________________________ mouse mammary cancer sc 4 8 mm 3.