Methods and compositions are provided for modulating, and generally upregulating, the expression of telomerase reverse transcriptase (TERT) by blocking repression of TERT transcription, e.g., by inhibiting binding of repressor factor to a Site C repressor binding site located in the TERT minimal promoter. The subject methods and compositions find use in a variety of different applications, including the immortalization of cells, the production of reagents for use in life science research, therapeutic applications; therapeutic agent screening applications; and the like. In further describing the subject invention, the methods and compositions of the invention are described first in greater detail, followed by a review of the various applications in which the subject invention finds use.