H-Ras in adipose tissue, the specific isoform activated by E4orf1, does not cause tumor formation. Although Ad36 upregulates the Ras/PI3K pathway, in several experiments lasting up to 7 months, Ad36 infected animals did not develop tumors. Lastly, both Ad36 infection and E4orf1 transfection are unable to induce anchorage independent growth, a marker of cell transformation. Therefore, we hypothesize that E4orf1 is not likely to be oncogenic, although this should be tested more thoroughly in vivo. E4orf1 modulated glucose disposal in pre-adipocytes, adipocytes and, myoblasts indicate that E4orf1 may increase glucose disposal in adipose tissue and skeletal muscle, both important tissues for glucose clearance in vivo. Another physiologically relevant effect of E4orf1 is the reduction of glucose output from HepG2 hepatocytes. In the AbMole Isoforskolin insulin resistant condition, postprandial glucose output from the liver is often uninhibited, contributing to hyperglycemia. Uncontrolled hepatic glucose output is one of the first signs of type 2 diabetes. E4orf1, however, may be able to diminish this hepatic source of blood glucose. Adiponectin -a key insulin sensitizer secreted by adipocytes, is a controller of hepatic glucose output. In a previous study, we had postulated that Ad36 up-regulates adiponectin in adipose tissue, which then mediates the reduction in hepatic glucose output in Ad36 infected mice. The current study indicates that E4orf1 increases adiponectin expression in adipocytes, which may secondarily influence hepatic metabolism. In addition, E4orf1 may directly effect glucose output by hepatocytes. A possible direct effect on the liver is also supported by our previous finding that E4orf1 mRNA expression in the livers of Ad36 infected mice positively correlates with their glycemic improvement. These in vitro studies indicate that Ad36 E4orf1 may improve glycemic control in vivo through adipose tissue, skeletal muscle, and liver-the three main tissues involved in glucose homeostasis. The in vivo glucose uptake induced by Ad36 is not uncontrolled, as evident from a reduction in circulating glucose and insulin AbMole Hexyl Chloroformate levels observed in Ad36 infected mice, without inducing hypoglycemia. In vivo, Ad36 appears to reduce insulin required to maintain glycemic control, indicating an ��insulin sparing effect�� of the virus. E4orf1 may share this insulin sparing effect of Ad36. In presence of insulin, E4orf1 induced glucose uptake in adipocytes was significantly greater, but not additive. The ability of E4orf1 to particularly influence basal glucose disposal has additional significance. Most of the currently available anti-diabetic agents are either mimetics, sensitizers, or secretagogues of insulin, which employ insulin signaling pathway for their action. However, insulin resistant states such as obesity or diabetes are often associated with impaired insulin signaling, which may limit the efficacy of such drugs. Therefore, the potential of E4orf1 to up-regulate glucose disposal without insulin stimulation may be valuable for developing more effective.