In this model, lineage-specific genes (a, b, and c) are in a primed state in the multipotent progenitor cells, characterized by open chromatin and some low-level of sporadic expression. Lineage-affiliated regulators (colored shapes) are initially coexpressed at levels that fluctuate within thresholds. This low-level multilineage gene activity establishes a ground state from which regulatory networks can develop through negative and positive feedback loops.