Endogenous substances, usually proteins, which are effective in the initiation, stimulation, or termination of the genetic transcription process.
Proteins that interact with each other and (somewhat) with DNA (when immediately adjacent to the DNA in a cell) to either facilitate (i.e., “turn on”) or inhibit (i.e., “turn off”) the activity (i.e., coding for proteins) of that DNA’s genes. Transcription factors hold potential to cure diseases (e.g., by blocking the deleterious effects of certain disease-causing genes).