Base your answer to this question on the following information: You have isolated a primary signal factor from the blood of a space alien, which you name XFF (for X-files factor). You also have Isolated various types of alien cells which appear to Interact with XFF. Based on preliminar data, you think that XFF could be similar to one of three compounds normally found in human blood: epidermal growth factor (EGF), epinephrine, or estrogen. Which of the following would best be used to demorstrate XFF is most like EGF? A. exposure of cells to tyrosine kinase inhibitors
B. microinjection into cells of nonhydrolyzable GTP analogues
C. exposure of cells to ryanodine
D. exposure of cells to radioactive XFF
E. receptor binding assays