A) PI3K/AKT/mTOR pathway is more active in ULMS, based on gene expression profiling data. Three previously described gene transcription signatures for the PI3K/AKT/mTOR pathway were applied to expression profiles of ULMS samples; each sample was scored for relative signature activity (heatmap is depicted: yellow = more active, blue = less active); B) Representative photographs of ULMS tissue microarray pS6RP, p4EBP1, and pAKT immunostaining (original images were captured at 400× magnification) depicting differences in expression between tumor and normal smooth muscle. Staining for PTEN is also shown and includes an example of PTEN expression loss as compared to positive staining – the later was observed in most evaluable samples; C) Western blot (WB) analyses demonstrate increased phosphorylation of the mTOR downstream effectors, S6K, S6RP, and 4EBP1, and the mTOR upstream regulator, AKT, in protein extracts of human ULMS cell strains/lines as compared to expression noted in normal smooth muscle cells (NSMC). Only Mes-Sa cells exhibited loss of PTEN expression.