Therefore, we proceeded to experimentally explore this hypothesis by inducing the overexpression of IDO1 and KYN in tumor cells with IFN‐γ stimulation and utilizing Stattic (a p‐STAT3 inhibitor that can inhibit STAT3 phosphorylation) as a positive control.[40] As shown in Figure 4Q, IFN‐γ stimulation led to high levels of IDO1 and STAT3 protein phosphorylation in 4T1 cells. Here, STAT3 is linked to neoplasm.