Probable phosphatase. Involved in the response to sodium and lithium ion stress (but not to potassium or sorbitol stress) by inducing transcription of the sodium pump ENA1/PMR2. Acts through a calcineurin-independent pathway and is functionally redundant with PSR1. Also involved in the general stress response; acts together with WHI2 to activate stress response element (STRE)-mediated gene expression, possibly through dephosphorylation of MSN2.