We have measured out-of-plane resistivity c for La 2Ϫx Sr x CuO 4 under anisotropic pressure. c-axis compression, which decreases c , reduces T c drastically, whereas c-axis extension, which increases c , enhances T c from 38 K at ambient pressure to 51.6 K at 8 GPa. We find that the variation of T c scales as a function of c , and that the c-axis pressure coefficient is much stronger than the ab-axis one. These findings imply that T c depends primarily on the interlayer, rather than the in-plane, lattice parameter.