Enzymic conversion. Murine mammary carcinoma 4T1 cells (104 cells/well) were cultured 96‐well plates in media with 5 µg/mL 6‐methoxypurine 2′‐deoxyriboside (MoPdR) for 96 h. The supernatants (0.1 mg/100 µL) of the tissues were incubated with 900 µL of 5 µg/mL MoPdR at 37°C for 24 h. Subsequently, lysates from the cells and tissues were analyzed for the concentrations of MoPdR in the supernatants by high‐performance liquid chromatography at a wavelength of 254 nm. 4T1‐SC/ePNP, right diagonal; 4T1‐SC/pEGFP, left diagonal; gastrointestinal tract‐SC/ePNP, white; liver‐SC/ePNP, hoar; spleen‐SC/ePNP, dark grey; tumor‐SC/ePNP, black.