Abstract: This invention relates to the functional characterization of myo-inositol monophosphatase 2 (IMPA2), one of the enzymes acting in the phosphatidyl inositol signaling pathway. In particular, the present invention provides evidence that IMPA2 is associated with depression- and anxiety inducing conditions, in particular anxiety and affective disorders. In a first aspect the present invention provides the use of an IMPA2 enzyme in an assay to identify anti-anxiety or an anti-depression compounds. In particular to the use of an isolated polynucleotide encoding said IMPA2 protein, wherein said IMPA2 protein is preferably being selected from polynucleotides encoding the mouse, rat or human IMPA2 enzyme.