A critical analysis on the conception of "Pre-existent gene expression programs" for cell differentiation and development

A pre-existent gene expression program at the basis of cell differentiation and development is often assumed in the current scientific literature. Historically this conception is traced to the nineteen sixties of the last century, when various influential papers and scientific personalities imprinted their view drawing inspiration from informatics. The accepted model is that in the presence of certain external and/or internal signals, a cell initiates a pre-determined program of gene expression by which it becomes differentiated. Authors generally do not question the evidence for the existence of such a program. Here I review different aspects and consequences of this model to conclude that it is completely at odds with the literature of the last decades, which has given us a splendid view of the dynamics of the living cell as an auto-organizing complex unit that is far away from thermodynamical equilibrium. In this view there is no place for programs.