Expression of an oncogenic mutant Gαi2 activates Ras in Rat‐1 fibroblast cells

Abstract
It has been reported that expression of the active mutant of heterotrimeric GTP‐binding protein α subunit Gαi2 transforms Rat‐1 cells. However, the Gαi2‐mediated mitogenic signaling pathways remain to be elucidated. Here, we demonstrate that inducible expression of the active mutant of Gαi2 (Gαi2(Q205L)) activates Ras and c‐Jun N‐terminal kinase (JNK) in addition to extracellular signal‐regulated kinase (ERK) in Rat‐1 cells. Our findings suggest that Ras may play a critical role in the Gαi2‐induced transformation and Gαi2 can transduce signals from the Gi‐coupled receptor to JNK and ERK in certain types of mammalian cells.