I presume you want to observe your protein gel by silver staining. However, ethidium bromide does not stain proteins. It is a nucleic acid  intercalating agent and thus used to stain nucleic acid gels (Agarose or Acrylamide). So, the direct answer to your query is that you cannot use EtBr as a staining agent in SDS-PAGE, but can stain native acrylamide gel used to run nucleic acid.

Hello Zahra,

Incorporating dyes (including Ethidium bromide) in vertical gel formats is not recommended for the dyes bind to glass/ plastic plates and cause very high background. Yes, DNA resolved on polyacrylamide gels can be post-stained with Ethidium bromide and detected.

Usually the practice is to stain the polyacrylamide gel after the resolution of the loaded molecule.

You can just sink the gel in the EtBr water after its resolution for viewing the band's.

If that is not possible the You can pre stain it. But that would not only leach it will also hamper resolution of molecules in gel.