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Comments
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TF-1a is a factor-independent variant isolated from the factor-dependent TF-1 cell line (see CRL-2003). The cells retain the ability to respond to a variety of cytokines, with a different response pattern from the parental cell line. TF-1a, but not TF-1 cells, form colonies in soft agar culture in the absence of any added growth factors, and generate invasive tumors in nude mice. There is a slight constitutive activation of the MAP kinase and MEK proteins in TF-1a but not in TF-1 cells. Phenotypically, TF-1 cells are CD34 positive and CD38 positive, whereas TF-1a cells are CD34 positive and CD38 negative. TF1-a cells, but not TF-1 cells, are resistant to tumor necrosis factor alpha (TNF-alpha) induced apoptosis. TF-1a is a model for studying human primitive myeloid progenitor cells and for studying the process of progressive malignant transformation of myeloid cells. It can be used to study signal pathways involved in the spontaneous and factor-induced growth of the cells. A culture submitted to the ATCC in April of 1999 was found to be contaminated with mycoplasma. Progeny were cured by a 21-day treatment with BM Cycline. The cells were assayed for mycoplasma, by the Hoechst stain, PCR and the standard culture test, after a six-week period following treatment. All tests were negative.
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