Caution: Effects of TANSHINS on Cytochrome P450 Isoforms. The cytochrome P450 enzymes are found primarily in the liver. TANSHINS (CTS) significantly increased the activity of CYP1A2 in a dose-dependent manner. In CTS groups at the dosages of 20 ~ 540 mg/kg, the activity of CYP1A2 was 60 % ~ 430 % higher, CYP1A2 protein expression level was 130 % ~ 320 % higher, and CYP1A2 mRNA expression level was 10 % ~ 150 % higher than that of the negative control group. CTS had no effect on other kinds of CYP isoforms. CTS can induce hepatic microsome CYP1A2 expression significantly, which indicates potential drug-drug interaction might occur when CTS is co-administrated with those drugs metabolised by CYP1A2 such as Capecitabine / Capecitabine (Xeloda), Lapatinib / Lapatinib (Tykerb) Traditional Chinese Drug Research & Clinical.