Despite a mixed cell population in terms of DOX responsiveness (Cas9 was predicted to be induced in ~25% of the population, as described above), deletion of SLC6A14/12A4 (Fig. 7f,g), and to a lesser degree SLC6A14/25A15 (Extended Data Fig. 6e), slowed tumor growth and conferred a survival benefit. Here, SLC6A14 is linked to neoplasm.