In the sentence extracted from biomedical literature, identify all the disease entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="disease"> to denote a disease.

### Input Text: Using this as immunogen , we prepared a panel of 12 monoclonal antibodies which recognise at least four different epitopes on emerin in order to ensure that emerin can be distinguished from non - specific cross - reacting proteins .
### Output Text:
Using this as immunogen , we prepared a panel of 12 monoclonal antibodies which recognise at least four different epitopes on emerin in order to ensure that emerin can be distinguished from non - specific cross - reacting proteins . 