Description of transitions between cellular phenotypes using transcriptional landscapes and networks. a) Cell transcriptional program landscape representing two attractors and the epigenetic barrier between them. This conceptual figure represents a cell stabilized in an initial cellular phenotype and how a hypothetical perturbation can destabilize the cellular program and make cell exceed the barrier and fell down in a final cellular phenotype. This cellular reprogramming is represented as a blue arrow from the initial to the final attractor. b) Cellular reprogramming as transitions between network states. Differentially expressed positive circuits (DEPCs) are perturbed to induce the transition from Attractor 1 to Attractor 2 passing by a transient state. This transient state can be considered as a “short” term changing expression pattern until the system reaches an attractor. Regular arrows represent activation and T-arrows represent inhibitions. Blue and red nodes represent inactive and active genes respectively in attractors. Violet nodes represent transient states.