Bcl11b, Notch1, and p38Map kinase protein expression in murine ETP-ALL versus classical T-ALL. (A) Bcl11b protein expression in nuclear extracts from spleens of ETP tumors that arose from the Il7R-241-242TC mutant (SP1-SP3) and GcinsL243 mutant (SP4). The last two lanes show nuclear extracts of spleens from a mature T-ALL tumor that arose from the Il7r-Gcins243 mutant (SP1) and a Lmo2 transduced hematopoietic stem cell induced CD4⁺CD8⁺ tumor (SP2). Lamin B serves as a loading control. (B) Bcl11b levels in a nuclear extracts from spleen samples of Lmo2-induced ETP tumors. Four tumors arising directly from the Lmo2 expression vector were analyzed for Bcl11b expression (SP1-4). The positive and negative controls are nuclear and cytoplasmic extract from a WT thymus, respectively. (C) Levels of the Notch1 intracellular domain (ICN1) were assessed in splenic ETP tumor cell extracts arising from the mutant Il7r receptors. Also shown is a tumor cell extract from a CD4⁺ CD8⁺ T-ALL case obtained with the GCins243 vector (T-ALL) and a Lmo2-induced classical T-ALL. Jurkat cells were used as positive controls and GPE-86 cells were used as the negative control (-ve). (D) Western blot analysis for Map kinase expression and activation (P-p38MAPK) in various murine ETP-ALL samples as indicated. For comparison, a case of CD4⁺ CD8⁺ T-ALL is included in the left hand lane.