Figure 6

AKT is constitutively phosphorylated, in a PTEN independent-manner, in a majority of LBLs and iMyc^Eμ-1 cells. (A) Western blot analysis of the activating-phosphorylation status of key proteins of the PI3K (AKT, P-AKT S473 and T308), MAPK (ERK 1/2, P-ERK1/2, total p 38, P-p 38) and mTOR (p70S6K, P-p70S6K) signaling pathways. Positive controls for P-ERK1/2, P-p38 and P-p70S6K were from extracts of UV-treated HeLa cells, NIH 3T3 cells and insulin-treated MCF-7 cells, respectively. (B and C) Levels of PTEN protein (B) and mRNA (C) in LBLs and iMyc^Eμ-1. α-tubulin and β-actin served as loading controls, respectively. "C" denotes control BL6 splenic B cells.