Western blot is done for:

Western Blotting detects Protein. Nohern Blotting detects RNA. Southern Blotting detects DNA. South-Western Blotting detects protein-DNA interactions. Technique Sample Analyzed Probe Southern Blot / DNA - DNA Hybridization DNA DNA Nohern Blot / RNA - DNA Hybridization RNA DNA Western Blot / Immuno Blot Protein Antibody South Western Blot Protein - DNA DNA Microarray mRNA or cDNA DNA ELISA Protein or Antibody Fig.: Basic Principle of Blotting