To study SH3BP2 function, we characterized three different cell lines derived from GIST patients: GIST882 (KIT exon 13 K642E), an imatinib‐sensitive cell line; GIST48 (KIT exon 11 D820A plus KIT exon 17 V560D), an imatinib‐resistant cell line; and GIST48B, a subline of GIST48, which, despite retaining the activating KIT mutation, expresses KIT transcript and protein at essentially undetectable levels (Muhlenberg et al., 2009). Here, KIT is linked to gastrointestinal stromal tumor.