Check cell
 

In Excel2000, I have budget templates that different areas fill in. In
one cell, we have them input sales $ and in the cell below thye input
profit %. I want to make sure that everytime they enter a sales $ they
are forced to enter a profit %. I don't want to put in a formula in the
Profit % cell because they then will input over the formula. Here is an
example:

Jan
Sales $ 100
Profit % 8%

Sometimes they forget the Profit % and it causes problems, like this:

Jan
Sales $ 100
Profit %

Anyone have any ideas on how I can insure an input?

Thanks