For example, in breast cancer cells represented by breast cancer stem cells and chemotherapy-resistant cells, there is a mammary adipocyte-derived leptin-LEPR-JAK-STAT3 signaling axis, and CPT2 is directly upregulated by the upstream transcription factor STAT3, which regulates chemotherapy sensitivity through the activation of the FAO pathway [91]. The gene discussed is LEPR; the disease is breast cancer.