The gene for the MyoD transcription factor is introduced into cultured fat cells. When the gene is expressed, the fat cells are transformed into muscle cells. What does this result imply about the fat cells and their commitment to the fat-cell fate?

The result implies that fat cells are committed to this fate, but not irreversibly determined.

Explanation:

The expression of Myod is capable of converting a fibroblast to a skeletal muscle cell. Due to the fact that it can do this, it is therefore a model system in developmental biology for studying how a single initiating event can orchestrate a highly complex and predictable response. Recent findings indicate that Myod functions in an instructive chromatin context and it regulates muscle cell differentiation by inducing cell cycle arrest, a prerequisite for myogenic initiation. The protein is also involved in muscle regeneration. It activates its own transcription which may stabilize commitment to myogenesis.