Try this:
For Excel versions 2003 and prior
Select the range of cells, A4:H4
Goto the menu Format>Conditional Formatting
Select the Formula Is option
Enter this formula in the box on the right:
=$O$4=1
Click the Format button
Select the desired style(s)
OK out
For Excel 2007:
Select the range of cells, A4:H4
Goto Home tab>Styles>Conditional Formatting>Manage rules>New rule>Use a
formula to determine which cells to format
Enter this formula in the box below:
=$O$4=1
Click the Format button
Select the desired style(s)
OK out