As described previously (Carbone et al. 2014 (link)), EBV-transformed cell lines were established from whole blood samples of an adult male Javan gibbon called Lionel at the Gibbon Conservation Center in Santa Clarita, CA. The blood was collected opportunistically during checkups and in agreement with protocols reviewed and approved by the Gibbon Conservation Center. Genome stability was established by karyotyping, which was carried out on metaphase chromosome spreads prepared per standard protocols. Briefly, slides were dehydrated in a 70%, 90%, and 100% ethanol row for 2 min each followed by air drying. Slides were stained with a 1:5 dilution of DAPI in Vectashield (Vector Laboratories, Inc., Newark, CA). Images were captured on an Olympus AX70 microscope and karyotyped using CytoVision software (Leica Biosystems Richmond, Inc., Richmond, IL) followed by manual review (Supplementary Fig. 1).