Here, using a transgenic mouse model and primary cell cultures along with quantitative PCR, immunoblotting, and immunohistochemistry, we tested whether the UPR is induced in <i>in vivo</i> and <i>in vitro</i> murine models of tauopathy that are based on expression of mutant tau<sup>P301L</sup> We found no evidence for the UPR in the rTg4510 mouse model, in which mutant tau is transgenically expressed under the control of tetracycline-controlled transactivator protein.