The Arabidopsis gene At5g21040 encodes a protein containing both WD40 and F-box motifs, termed FBX2. A T-DNA insertional mutant in this gene was obtained. Analysis of this mutant line showed that FBX2 is a negative regulator of several Pi starvation responses. FBX2 interacts with BHLH32, another negative regulator of Pi starvation responses. We suggest that FBX2 may be part of an SCF-like complex that recruits BHLH32 and its partners, potentially targeting the latter for proteolysis.