Differential responsiveness of exon 9 and exon 11 Kit mutations to HG-7-85-01. (A) Comparison of HG-7-85-01 responsiveness of primary Kit mutants, exon 9 kit (insAY) and exon 11 Kit (delWK, V559), with or without secondary Kit mutants, exons 13, 14, and 17 (2.5- to 3-day treatments). (B) HG-7-85-01 treatment of delWK (± IL-3), delWK + V654A (−IL-3), and delWK+T670I (−IL-3) (2.5-day treatment). (C) HG-85-01 treatment of V559D and delWK + Y823D (−IL-3) (2.5-day treatment). (D) HG-7-85-01 treatment of Kit mutants in the absence and presence of IL-3. Error bars represent the SEM for proliferation studies performed in duplicate.