We have measured the 12C(e,e'p)11B reaction in parallel and antiparallel kinematics over a p_m range of -120 < p_m < 120 MeV/c and a central T_p of 90 MeV. In contrast to previous measurements at NIKHEF, both kinematics can be described without enhancement of the transverse form factor of the bound proton (eta=0.98). The spectroscopic factor for this transition as determined with the new Mainz data is 22% smaller than the NIKHEF value.