Pten (phosphatase and tensin homolog deleted on chromosome 10) protein localizes to multiple subcellular compartments. Pten conditional knockout brains contain Pten-positive and Pten-negative neurons, providing internal controls for immunohistochemical detection of Pten. In mature neurons of the cerebral cortex, Pten is present in the nucleus, the soma, and the neuronal projections (yellow arrowheads). Pten-deficient neurons show global hypertrophy, and the absence of Pten is seen clearly in all cell compartments (red arrowheads). Immunohistochemical detection of Pten was performed with anti-Pten antibody from cell signaling (#9559), peroxidase-labeled secondary antibody, diaminobenzidine (DAB) substrate, and hematoxylin counterstain.