Cell development is more than just cell specification - cells must mature by Scaling up certain properties. During development, cell fates are first determined by the transient, sequential expression of transcription factors (TFs). In this fictive example, a 3-step linear pathway restricts a cell to produce a specific but immature “Gold” cell – Cell Specification, upper. However, a truly mature cell has scaled its specific features to optimally perform its physiological functions. The transition from immature to mature Gold cell differentiation involves a set of poorly understood processes that we term “Scaling” – Cell Maturation, lower.