p18(Ink4c) functions as a dedicated inhibitor of cyclin-D-dependent kinases. Loss of Ink4c predisposes mice to tumor development and, in a dose-dependent manner, complements the tumor-promoting effects of various oncogenes. We have now addressed whether Ink4c loss impacts B-cell tumor development in the Emu-Myc transgenic mouse, a model of human Burkitt lymphoma. Loss of one or both alleles did not influence the onset of lymphoma in Emu-Myc transgenics, and did not appreciably affect Myc's proliferative or apoptotic responses in precancerous B cells. Nevertheless, Ink4c loss modulated the effects of Myc-induced transformation by decreasing the frequency of Arf loss, an ordinarily common event in Emu-Myc-induced lymphomas.