  One of the fundamental cellular processes governed by genetic regulatory
networks in cells is the transition among different states under the intrinsic
and extrinsic noise. Based on a two-state genetic switching model with positive
feedback, we develop a framework to understand the metastability in gene
expressions. This framework is comprised of identifying the transition path,
reconstructing the global quasi-potential energy landscape, analyzing the
uphill and downhill transition paths, etc. It is successfully utilized to
investigate the stability of genetic switching models and fluctuation
properties in different regimes of gene expression with positive feedback. The
quasi-potential energy landscape, which is the rationalized version of
Waddington potential, provides a quantitative tool to understand the
metastability in more general biological processes with intrinsic noise.
