Before revision: Progress in cell reprogramming recently has revived Waddington's concept of an epigenetic landscapein the term of a quasi-potential function and cell attractors in a complex dynamical system embodied by the cell's gene regulatory network (GRN) . The quasi-potential of network states have biological significance because the relative stability  in a multi-stable dynamical system offers a measure of the effort for the transition between attractors .
After revision: Progress in cell type reprogramming has revived the interest in Waddington's concept of an epigenetic landscapein the term of a quasi-potential function and cell attractors in a complex dynamical system embodied by the cell's gene regulatory network (GRN) . The quasi-potential of network states have biological significance because the relative stability in a multi-stable dynamical system offers a measure of the effort for the transition between attractors .