In fast muscle of pacu, a fasting period promoted an increase in the expression of the catabolic genes ATG12 (Related Autophagy 12/Ubiquitin-like), BCL2 (B-cell CLL/Lymphoma 2) and FBXO25 (F-Box Protein 25/ubiquitin protein), the anabolic gene PI3K (Phosphatidylinositol 3 Kinase, Catalytic Subunit Type 3), and the mTORC1 complex components, mLST8 (Target of rapamycin subunit complex LST8), mTOR (Target of Mechanistic Rapamycin) and RAPTOR (subunit complex mTORC1), compared with the C group. The gene discussed is FBXO25; the disease is B-cell chronic lymphocytic leukemia.