Stellar kinematics and line-strength indices as measured along the major axis of NGC 4138. The radial profiles of the line-of-sight fourth- and third-order coefficient of the Gauss-Hermite decomposition of the LOSVD (h₄ and h₃); velocity dispersion (σ); velocity (v) after the subtraction of systemic velocity; and the line-strength indices Fe₅₃₃₅, Fe₅₂₇₀, Mgb, Mg₂, and Hβ are plotted (from top to bottom). The red and blue dots indicate the receding (NW) and approaching (SE) side of the galaxy, respectively.