The RPS4X antibody targets the ribosomal protein S4. X-linked (RPS4X), a component of the 40S ribosomal subunit essential for mRNA translation. Located on the X chromosome, RPS4X encodes a conserved ribosomal protein involved in ribosome assembly and protein synthesis. Unlike its Y-linked homolog RPS4Y, RPS4X escapes X inactivation, leading to higher expression in females. This protein is critical for cellular proliferation and homeostasis, with dysregulation linked to cancer, autoimmune diseases, and X chromosome-related disorders. Antibodies against RPS4X are widely used to study its expression, localization, and function in various tissues. In research, they help detect RPS4X in Western blotting, immunohistochemistry, and immunofluorescence, aiding investigations into ribosomal biology and disease mechanisms. Notably, RPS4X overexpression has been observed in certain cancers, while autoantibodies against RPS4X are detected in autoimmune conditions like systemic lupus erythematosus (SLE), suggesting its role in immune dysregulation. Studies also explore its interaction with viral RNAs and potential involvement in antiviral responses. The RPS4X antibody serves as a tool to unravel sex-specific differences in disease susceptibility and therapeutic responses, reflecting the protein's unique genetic and functional characteristics.