We infected Kras+/LSL-G12D mice with viruses carrying either Ad5-CMV-Cre or Ad5-CMV-βgal (control) for up to 20 weeks (Fig. 3A), or with Ad5-mSPC-Cre for up to 40 weeks (Fig. 3B), by intranasal delivery, and monitored tumour development every 2 weeks in the case of Ad5-CMV-Cre/Ad5-CMV-βgal, and every 5-10 weeks in the case of Ad5-mSPC-Cre, by micro-CT scanning (Fig. 3A,B, right panels). Here, KRAS is linked to neoplasm.