In addition, among the LNCaP xenograft tumours we collected, both TDO2 and AhR proteins were significantly upregulated in tumours that recurred after castration compared with normal tumours (Fig. 3f), and the mRNA levels of TDO2, AhR, and CYP1A1 were also significantly elevated (Supplementary Fig. S10f). Here, AHR is linked to neoplasm.