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: Exposure of normal human cells to gamma - irradiation and the radiomimetic drug neocarzinostatin had no effect on ATM protein levels , in contrast to a noted rise in p53 levels over the same time interval .
### Output Text:
Exposure of normal human cells to gamma - irradiation and the radiomimetic drug neocarzinostatin had no effect on ATM protein levels , in contrast to a noted rise in p53 levels over the same time interval . 