Complete the letter analogy: MNO : RQP :: DEF : ?

Two things are done together: every letter moves on 3 places, and the group is then written in reverse. M, N, O move on to P, Q, R, which written backwards reads RQP. D, E, F move on to G, H, I, which written backwards reads IHG. 'GHI' makes the move of 3 but forgets to turn the group round; 'HGF' turns it round after a move of only 2; 'JIH' turns it round after a move of 4.