Skip to main content
. 1999 Oct 1;13(19):2562–2569. doi: 10.1101/gad.13.19.2562

Figure 2.

Figure 2

Models for SUR-6 PP2A-B function in the vulval induction pathway. (A) SUR-6 PP2A-B is likely to regulate the activity of a PP2A core complex composed of a C and A subunit to influence Ras signaling. SUR-6 PP2A-B is a positive regulator of Ras signaling, so SUR-6 could function either to activate the PP2A core, which in turn activates Ras signaling, or to inhibit the PP2A core that normally inhibits Ras signaling. Potential targets for SUR-6 PP2A-B-regulated PP2A activity include LIN-45 Raf and KSR-1. (B) Model for the signal transduction pathway regulated by SUR-6. The receptor tyrosine kinase LET-23 is activated by an inductive signal that leads to the activation of LET-60 Ras. Ras–GTP recruits Raf kinase to the membrane and Raf phosphorylates and activates the MEK-2 MEK/MPK-1 MAPK kinase cascade. We showed that SUR-6 PP2A-B positively regulates signaling at a branch point at the level of Ras or Raf. KSR-1 and SUR-6 may work together to strengthen Ras pathway output during vulval cell fate specification.