Deletion of <i>Pten</i> induces cell proliferative advantage in prostate tissues.

<p><b>A–I.</b> Cell proliferation was examined by immunostaining for Ki-67. Prostate sections isolated from 4-week-old <i>Pten^loxP/loxP</i>, <i>Pten^loxP/+:Osr1-Cre,</i> and <i>Pten^loxP/loxP Osr1-Cre</i> mice were stained for Ki-67. A total of 1000 epithelial cells in each lesion from three different lesions from three mice of each genotype were evaluated for Ki-67 immunoreactivity. <b>J.</b> The positive immunoreactive cells for Ki-67 in <i>Pten^loxP/loxP</i>:<i>Osr1-Cre+</i> mice are significantly greater than both <i>Pten^loxP/loxP</i> control mice and <i>Pten^loxP/wt:Osr1-Cre</i> mice, P<0.01.