Nmri nu nu

2427PT cells (3.5 10⁵ cells in 200 μl PBS/matrigel (1:1 v/v; Becton Dickinson, Heidelberg, Germany)) were subcutaneously injected in 7-week old female homozygous Naval Medical Research Institute nude mice (NMRI nu/nu; Charles River, Sulzfeld, Germany). 3 weeks after injection, oral administration of Compound A (30 mg/kg in 0.1% (v/v) Tween80 and 0.5% (w/v) carboxymethylcellulose in water (v/v)) via oral gavaging twice a day was started for 3 weeks. Control mice were treated twice daily with vehicle only.
KLN205 cells (5 10⁵ cells in 100 μl PBS) were subcutaneously injected in 9-week-old male DBA/2 mice (Janvier, Le Genest St. Isle, France). Once tumor volume was approximately 150 mm³ daily intra-tumoral injection of ELOVL6 inhibitor (10 μM in PBS) versus control (DMSO in PBS; 0.1% final concentration) was started for 14 days.
Tumors were measured twice a week using a caliper when mice were anesthetized (1.5-2% isoflurane in 100% oxygen). The tumor volume was estimated via the formula 0,52 x a x b² (with a = largest diameter and b = smallest diameter).

A patient-derived xenograft (PDX) model, PG48, was developed from the regorafenib-resistant GIST patient #1. This PDX has a homozygous KIT exon 11 primary mutation (V559D) and a homozygous KIT exon 13 secondary ATP-binding pocket mutation (V654A). All in vivo work was conducted under appropriate Institutional Animal Care and Use-Committee-approved protocols. Six- to 8-week-old female adult athymic nude mice (NMRI nu/nu) were obtained from Charles River Laboratories (Wilmington, MA, USA) and housed under specific pathogen-free conditions. Tissue fragments of PG48 were serially passaged in donor mice injected subcutaneously in each rear flank. In all studies, vehicle control or study drugs were administered orally once daily. Solutions and drug doses were as follows: sterile water, and 100 mg/kg/day for Imatinib; citrate buffered (pH 3.5), and 40 mg/kg/day for sunitinib^{25 (link)}; PEG400/125 mM aqueous methanesulphonic acid (80/20), and 30 mg/kg/day for regorafenib.^{15 (link)} The experiment was stopped after 3 days of treatment, mice were sacrificed, and tumours were harvested for protein analysis.

P73-micro scaffolds (Ø = 6 mm²) were implanted on the right tibialis anterior (TA) muscles of 6-week-old male wild-type C57BL/6 (Charles River, Beerse, Brussels, Belgium) mice. Six-week-old male athymic nude (NMRI, nu/nu, Charles River, MA, USA) and scid/mdx mice, congenitally lacking B and T lymphocytes [64 (link)], were also used to assess the biocompatibility of the scaffold (Supplementary Figure S2). The contralateral muscles were sham-operated and used as internal control. To study the response of the scaffold under acute muscle degeneration, TA muscles of nude mice were freeze-injured by a dry ice precooled steel probe (Ø = 6 mm²) applied on exposed muscle for 10 s. Mice were euthanised 4 and 6 weeks after muscular P73-micro implantation. All the in vivo experiments were performed in accordance with ARRIVE guidelines and following the three Rs rule of Replacement, Reduction, and Refinement principles [65 (link)]. Mice were treated with protocols approved by the animal experimentation ethics committee of the KU Leuven, Belgium (P057/2017, 6 Mar 2017).