KLF4 and chronic myelogenous leukemia, BCR-ABL1 positive: The HAP1 cells are a single clone of the almost-haploid KBM7 (chronic myelogenous leukemia) cell line infected with a retrovirus cocktail containing SOX2 (SRY-box transcription factor 2), c-MYC (Avian myelocytomatosis virus oncogene cellular homolog), OCT4 (Octamer-binding transcription factor 4), and KLF4 (Kruppel-like factor 4) to induce pluripotency.