Is there a formula to highlight all duplicate cells from a selected cell?

Cell A1 aaa
Cell A2 bbb
Cell A3 8888
Cell A4 bbb
Cell A5 bbb
Cell A6 8888
Cell A7 8888

When I select bbb in Cell A2, I want the font in Cell A2, A4 and A5
highlighted. Likewise, if I select ccc in Cell A3, I want the font in Cell
A3, A6, A7 hightlighted.