Figure 3.

Mechanism of action of activators, insulin concentration response. Cells were pretreated with increasing concentrations of insulin; compounds were added at saturating concentrations, and cells were incubated for 1 h. Cells were placed on ice, and cell-surface Glut4 was determined. The shapes of the curves distinguish insulin mimetics, insulin-sensitizers, dis-inhibitors, and drugs that work through parallel (insulin-independent) pathways. A, all compounds increase cell-surface Glut4 ∼2-fold at sub-maximal (0.3 nm) insulin (red oval). B, drug classes are distinguished by their effects on cells preincubated at low (0.003 nm) and saturating (100 nm) insulin (summarized in Table 2).