THE TRANSFORMING ACTIVITY OF ACTIVATED G-ALPHA-12

Heterotrimeric GTP-binding proteins transduce receptor-mediated extrac ellular signals to their effectors. Several activated mutations of Gsa lpha and Gialpha have been shown to be associated with endocrine tumor s. In this report, we have evaluated the transforming activity of an p utative activated form of Galpha12 subunit. We found that transient ex pression in NIH3T3 cells of the Galpha12 mutant with substitution of g lutamine-229 for leucine could lead to focus formation and that stably transfected NIH3T3 cells could form colonies in soft agar and tumors in nude mice.