GSTM4 and hydrops fetalis: Proteomic profiling revealed the significant upregulation of anti-apoptotic proteins (HSP90AB1, FLNA), antioxidants (PRDX2, GSTM4), and energy metabolism-related proteins (ATP-dependent chaperones HSPA1A, HSPA2, CCT family members CCT7/CCT8/CCT6A/CCT6B) in HF bulls.