I had a look at N. Berkovits & L. Motl, Cubic Twistorial String Field Theory, hep-th/0403187 I have to admit that I am (still) not familiar with strings in twistor space, so let me ask a stupid question: What about worldsheet supersymmetry? Is there any? If yes, why does the BRST operator look the way it does in equation (2.4)? If not, why can we still have a relation to SYM? Another question: I have a basic understanding of ordinary cubic bosonic open string field theory. What is, heuristically, the physical interpretation of the new cubic interaction term in equation (3.19)?