As there is no table I'm going to attempt to explain in such a way that yo can solve it.
2-mercaptoethanol is used to denaturate proteins converting them in elongated proteins and, therefore, having them migrate at different rates in the gel depending only on their size. In the absence of 2-mercaptoethanol, the proteins are not elongated, mattering to their migration not their size but their 3D conformity. The proteins that would probably migrate together during sds-page in the absence of 2-mercaptoethanol would be those that have a similar 3D conformity.
