Provided herein are engineered TSC2 polypeptides, and nucleic acid sequences encoding them, in which the ability of a serine residue to be phosphorylated is altered. In some aspects, the TSC2 serine residue cannot be phosphorylated (e.g., by substituting the serine residue with an alanine residue). In some aspects, the TSC2 serine acts as if it is constitutively phosphorylated (e.g., by substituting the serine residue with a glutamic acid residue). Also provided herein are engineered immune cells comprising altered TSC2 polypeptides or nucleic acid sequences encoding them, and methods of making and using such engineered immune cells.