PTEN and neoplasm: The tumor volume in GFP-PTEN4A-inoculated mice was significantly smaller than that in GFP-inoculated or GFP-PTENWt-inoculated mice (Figure 8B), indicating that four-Ala substitution of phosphorylation sites in the C-terminus of PTEN expressed in tumors inhibited tumor growth in vivo, in part due to the combined effects shown in the above in vitro experiments.