Plays a role in differentiation. Specifically expressed in cells differentiation from the PS point, a specific point from which cells enter the differentiation phase in response to starvation. Not present in the exponentially growing cells, starts to accumulate within 2 hours following removal of growth medium, reaching a peak at 4 hours then disappearing. Overexpression rather impaired the progression of differentiation. Antisense RNA-mediated dia1 inactivation was found to enhance the initial step of cell differentiation.