  We show that for lattice-mismatched zinc-blende-type (110)-grown quantum
wells a significant contribution to the zero-magnetic-field spin splitting of
electron subbands comes from strain-induced spin-orbit coupling. Combining
envelope function theory and atomistic tight-binding approach we calculate
spin-orbit splitting constants for realistic quantum wells. It is found that
the strain due to lattice mismatch in conventional GaAs/AlGaAs structures may
noticeably modify the spin splitting while in InGaAs/GaAs structures it plays a
major role and may even change the sign of the spin splitting constant.
