Recent studies on written word production aim at studying how information is transmitted between central (linguistic) and peripheral (motor) processes. Neurocognitive models propose that the interface between both types of processes would rely on a frontal writing center (i.e. the GMFA or "Exner's area"). However there is still debate (1) whether those "levels" are processed in a serial or a cascaded/parallel way and (2) about the nature of the contribution of the GMFA. In Experiment 1, we evaluated the interaction between length and orthographic consistency effects in a writing-to-dictation task. We observed consistency effects on latencies and writing speed depending on the position in the word of the inconsistent segment. In Experiment 2, 16 participants underwent a writing-to-dictation task, manipulating length and regularity effect, after inhibitory rTMS. We observed an increase of latencies restricted to long and irregular words. Those results are consistent with a cascaded view of writing and suggest a more complex role of GMFA than initially expected.