Once tumors were fully established (average tumor volume: 100 mm3), optical titanium imaging windows were surgically implanted74,75, mice were administered with a single dose of gemcitabine/Abraxane on day 3 post-surgery (Fig. 8a) and imaging of CDK1 activity in cancer cells was performed over three days post-treatment (Fig. 8a). Here, CDK1 is linked to neoplasm.