Is there any way of flagging blank cells within a spreadsheet?

Normally when one of the cells within any one row is populated, there are
additional cells in that same row that also needs to be populated in order
for the calculations/formulas on subsequent worksheets to work.

For example if one of these cells - X4, AL4, AZ4, BN4, CB4, CP4, DD4, DR4 -
is populated, I'd like some sort of flag to ensure that the remaining cells
in this range are also populated.

Any ideas?

Thanks in advance