Krüppel-like factor 6 (KLF6) RNA silencing reveals that KLF6 protein expression was successfully repressed, particularly by siRNA3, which was used in subsequent experiments (a). (b) KLF6 RNA silencing resulted in (i) increased MyoD and myogenin protein levels, (ii) enhanced MCK Luciferase activity and, (iii) reduced transforming growth factor β (TGFβ) induced cell proliferation. (c) Cell proliferation was measured using the MTT cell proliferation assay kit. The number of proliferating cells is directly proportional to the absorbance at 570 nm. TGFβ treatment doubled the number of proliferating cells and this effect was repressed with KLF6 silencing. (d) A schematic summary of the data presented, in which TGFβ/Extracellular signal regulated kinase (ERK) signaling represses myogenic differentiation while TGFβ/Smad signaling regulates KLF6 gene expression and myoblast proliferation.