Figure 2: RA synergizes with insulin to induce Gck expression
and attenuates insulin-suppressed Pck1 expression. RA induces
the expression levels of Gck and Pck1 via the activation of both
RAR/RXR (the oval dimmers on the RAREs) in the absence of
insulin. Insulin alone stimulates the expression of Gck and
suppresses the expression of Pck1. In the presence of both
insulin and RA, the expression of Gck is further increased
(synergy). On the other hand, the insulin-mediated suppression
of Pck1 expression is attenuated. This is because RA still
induces Pck1 expression via activation of RAR in the presence of
insulin. Therefore, Pck1 transcript level in the RA + insulin
group is higher than that in the insulin group (attenuation).