C/EBPα-C^m, but not C/EBPα-N^m, immortalized BM cells. (A) Expression of C/EBPα-C^m, C/EBPα-N^m, or C/EBPα-p30 in BM cells transduced with Myc-tagged C/EBPα-C^m, C/EBPα-N^m, C/EBPα-p30, or mock (pMXs-IP). Cell lysates were subject to immunoblotting with anti-Myc Ab or anti-tubulin Ab as control. The results shown are representative of 3 independent experiments. (B) Colony-forming assay from BM cells transduced with C/EBPα-C^m, C/EBPα-N^m, C/EBPα-p30, or mock (pMXs-IP). Bars represent the number of colonies obtained per 10⁴ cells after each round of plating in methylcellulose supplemented with stem cell factor, thrombopoietin, IL-3, and IL-6. Data are representative of 3 independent experiments. All data points correspond to the mean and the standard deviation (SD) of 3 independent experiments. (C) Cytospin preparations of immortalized BM cells transduced with C/EBPα-C^m were stained with Giemsa. Images were obtained with a BX51 microscope and a DP12 camera (Olympus); objective lens, UplanFl (Olympus); original magnification ×100.