How could I copy cells in a range but reverse its sign?

E.g To Copy Range A2:D2 to A1:D1
The value in A2= 15000
The value I wish then to see in A1 = -15000
Same for B2:D2 etc
There maybe <blanks in cells A2:D2 if so I would still want these
blank in A1:D1

Thanks