Expression of KIT receptor in transduced Ba/F3 cells, and hyperproliferative response of representative exon 8 mutants to SCF. (A) The expression of the indicated KIT constructs in Ba/F3 cells was confirmed by Western blotting using a polyclonal KIT antibody (α KIT) as described previously.18 The β-Actin reblot (αβ-Actin) served as a control for protein loading. (B-C) Ba/F3 cells transduced with the indicated constructs (B: •, D816V; ○, T417I/Δ418_419; ▾, KIT-WT) were grown in the presence or absence of SCF as indicated (C: open bars, no factor; light gray bars, 1 ng/mL; dark gray bars, 10 ng/mL; filled bars, 100 ng/mL) and counted after 72 hours in a standard hemacytometer after staining with trypan blue. All values obtained from D816V and T417I/Δ418_419 cell lines and all values of Δ419 and Δ418_419 labeled with an asterisk were significantly different from the corresponding wild-type value (P < .05). Figures show mean values and SDs from 3 independent experiments. Data were statistically tested using a 2-sided paired t test (Excel, Microsoft, Redmond, WA).
