Figure 2.

PTEN expression in the intestine and the impact of PTEN inactivation on the activity of the PI3K-Akt pathway and on the expression of cell cycle regulators. (a–c) Dual immunofluorescence using a pan-PTEN antibody to detect both p-PTEN and non-p-PTEN and an antibody to BrdU to detect pulse-labeled cells. PTEN protein is detected in portions of the transit amplification compartment that are not actively cycling (b). PTEN is also highly expressed in the ISC position (c). The left and right boxes in a are shown at higher magnification in b and c, respectively. (d) Protein blot and RT-PCR analysis of PTEN-deficient intestine. Top and bottom panels (protein blots) demonstrate increased levels of p-Akt and p-GSK3β (top) and cyclinD1 (bottom). An RT-PCR assay also showed increased levels of Myc and cyclinD1 (center panel). (e) Microarray assay analysis showing changes in cell cycle-related genes in the PTEN-deficient mouse. Heat map represents signal of an individual sample relative to the average of all five samples. Asterisk indicates genes identified with the BioCarta term ‘cell cycle: G1/S checkpoint’.