PTEN and neoplasm: By contrast, tamoxifen-treated mice harboured tumours with high levels of Sca1 and NGFR, and the population of Sca1+/NGFR+ cells was the same proportion of tumour as found in the pure Lkb1/Pten SCC tumours (P=0.004 Tam versus no Tam, P=0.720 Tam versus Lkb1/Pten).