Morphology of cells used throughout the experiments. Morphology of cells used throughout the experiments. (A) Human visceral preadipocytes were differentiated for 10 days according to the manufacturer's protocol. Next, the cells were stained with Oil Red O and visualized under phase contrast microscope. Magnification ×250. (B) Human skeletal muscle cells (Lonza) were differentiated for 5 days in Dulbecco's modified Eagle's medium (DMEM) medium + 2% horse serum. The cells were fixed in ice-cold methanol and stained with DAPI and anti-desmin-Alexa Fluor488 antibody. Fluorescence microscopy, magnification ×200. DAPI (left panel) and antidesmin stain (right panel). (C) Human skeletal muscle myoblasts (Lonza) were differentiated for 5 days in DMEM medium + 2% horse serum. The cells were fixed in ice-cold methanol and stained with DAPI and anti-desmin-Alexa Fluor488 antibody. Fluorescence microscopy, magnification ×200. DAPI (left panel) and antidesmin stain (right panel). Dominika Nowis et al. BMJ Open Diab Res Care 2014;2:e000017 ©2014 by American Diabetes Association