On the assertion that PCT violation implies Lorentz non-invariance
  Out of conviction or expediency, some current research programs take for granted that "PCT violation implies violation of Lorentz invariance". We point out that this claim is still on somewhat shaky ground. In fact, for many years there has been no strengthening of the evidence in this direction. However, using causal perturbation theory, we prove here that when starting with a local PCT-invariant interaction, PCT symmetry can be maintained in the process of renormalization. 
Michael Duetsch, Jose M. Gracia-Bondia
hep-th hep-ph math-ph math.MP