Figure 6.

The dominant-negative effect of STAT3-YF in the IL-6-induced STAT3 signaling pathway. The dominant-negative effect of STAT3-YF (red) on the WT-STAT3 (blue) activity in the cells relies on: 1) Competition in binding to phosphotyrosine motifs of the activated gp130-receptor 2) Formation of inactive, semiphosphorylated, non-DNA-binding heterodimers after IL-6 stimulation 3) Formation of preformed dimers between STAT3-YF and WT-STAT3 in the absence of IL-6 which reduces the capability of STAT3 to form active, DNA-binding homodimers after stimulation.