In a study involving the fruit fly equivalent of an oncogene implicated in many human leukemias, a research team has gained insight into how developing cells normally switch to a restricted, or specialized, state and how that process might go wrong in cancer. The researchers were surprised to discover that levels of an important protein start fluctuating wildly in cells during this transition period. If the levels don’t or can’t fluctuate, the cell doesn’t switch and move forward.