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: These findings indicate that the ATM gene product plays an essential role in a diverse group of cellular processes , including meiosis , the normal growth of somatic tissues , immune development , and tumor suppression . .
### Output Text:
These findings indicate that the ATM gene product plays an essential role in a diverse group of cellular processes , including meiosis , the normal growth of somatic tissues , immune development , and <span class="disease">tumor</span> suppression . . 