Christian Baumgartner

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The Raf/MEK/ERK and PI3K/Akt pathways are prominent effectors of oncogenic Ras. These pathways negatively regulate each other, but the mechanism involved is incompletely understood. We now identify MEK1 as an essential regulator of lipid/protein phosphatase PTEN, through which it controls phosphatidylinositol-3-phosphate accumulation and AKT signaling. MEK1(More)
BACKGROUND AND OBJECTIVES In a majority of all patients with systemic mastocytosis (SM) including those with mast cell leukemia (MCL), neoplastic mast cells (MC) display the D816V-mutated variant of KIT. The respective oncoprotein, KIT D816V, exhibits constitutive tyrosine kinase (TK) activity and has been implicated in malignant cell growth. Therefore,(More)
More than 30% of all human cancers contain activating mutations of the small G-protein RAS. As a result of this, RAS has been intensely studied and many efforts have been made to identify pathways that sustain RAS-driven transformation [1]. Recent studies have indicated that the transcription factor GATA2 is one of these partners in crime, but a mechanistic(More)
Systemic mastocytosis (SM) is a myeloid neoplasm involving mast cells (MCs) and their progenitors. In most cases, neoplastic cells display the D816V-mutated variant of KIT. KIT D816V exhibits constitutive tyrosine kinase (TK) activity and has been implicated in increased survival and growth of neoplastic MCs. Recent data suggest that the proapoptotic(More)
Dasatinib is a multitargeted drug that blocks several tyrosine kinases. Apart from its well-known antileukemic activity, the drug has attracted attention because of potential immunosuppressive and anti-inflammatory effects. We report that dasatinib at 1 microM completely blocks anti-IgE-induced histamine release in blood basophils in healthy donors, and(More)
Specific inhibitors of PI3K isoforms are currently evaluated for their therapeutic potential in leukemia. We found that BCR/ABL(+) human leukemic cells express PI3Kdelta and therefore explored its impact on leukemia development. Using PI3Kdelta-deficient mice, we define a dual role of PI3Kdelta in leukemia. We observed a growth-promoting effect in tumor(More)
An immunotherapy trial performed in allergic patients with hypoallergenic recombinant fragments, comprising aa 1-74 and 75-160 of the major birch pollen allergen, Bet v 1, has indicated that the induction of allergen-specific IgG responses may be an important mechanism of this treatment. To investigate whether the immunogenicity of the rBet v 1 fragments(More)
BACKGROUND Lineage involvement and maturation arrest are considered to have prognostic significance in patients with myelodysplastic syndromes (MDS). However, although the prognostic value of neutropenia, thrombocytopenia, and monocytosis have been documented, little is known about the impact of eosinophils and basophils. METHODS The authors examined the(More)
Criteria, scoring systems, and treatment algorithms for myelodysplastic syndromes (MDS) have been updated repeatedly in recent years. This apparently results from increased awareness and early recognition of the disease, an increasing number of new diagnostic and prognostic markers and tools, and new therapeutic options that may change the course and thus(More)