Inhibition of the protein phosphatase 2A (PP2A) family of serine-threonine phosphatases contributes to human cell transformation. Depletion of PP2A complexes containing the PP2A B56gamma regulatory subunit in immortalized human cells induces cell transformation in vitro. To examine the function of PP2A B56gamma complexes, we applied tandem affinity purification and mass spectrometry to detect proteins that bind to PP2A B56gamma. We identified liprin alpha1 as a novel PP2A B56gamma interacting protein. B56gamma-liprin alpha1 complexes are distinct from PP2A complexes containing B56gamma. Consistent with this finding, liprin alpha1 does not directly contribute to cell transformation. However, suppression of liprin alpha1 by RNA interference alters cell morphology. These findings suggest a novel role for PP2A B56gamma independent of its regulation of PP2A activity.