IGF-1 stimulates the proliferation of Ba/F3, but not DA-3 cells. Short-term IGF-1 dose response studies were performed with three individually isolated Ba/F3 cell clones (parental, ▪; Ba/F3-WT 1, •; Ba/F3 WT 8, ▾) and three individually isolated DA-3 cell clones (DA-3-WT 3, □; DA-3 WT 6, ○; and DA-3-WT 17, ▵) in SS. Data points represent the mean ± SE of triplicate determinations.