Conditional Formatting based on formatting in multiple worksheets

If there's another posting that answers this, just let me know; I'm not really sure where to start looking.

Is it possible to apply conditional formatting in Sheet1 to match formatting across other sheets?

For instance, Sheet1 is a master sheet, and contains all of the rows spread out across Sheets 2-4. If I highlight a value in Sheet4 that also appears in Sheet1, I want it to automatically highlight in Sheet1. Is this possible?

Thanks in advance for your help!

If push came to shove, I could run a macro every couple of minutes. Do you have any idea what that would look like?