IsEmpty for multiple cells

You can do something like this:

Dim cell as range
for each cell in Range("B2,C3,D4,E5").Cells
  If IsEmpty(cell.Value) = True Then
    dim Incomplete as Boolean
    Incomplete = True
    cell.Font.ColorIndex = 3
    end if
next cell
If Incomplete then
MsgBox "Please Complete Mandatory Fields"
else
' rest of code