Read in matching transcription factor target gene pairs.
In case the user is able to provide a file with transcription factor - target gene matches (e.g. from TRANSFAC database) this function can read in the information. The file needs to be a txt file with first column transcription factors and second column target gene symbols without a header.
path of txt file containing the transcription factor target gene information as specified above.
data frame with user-specified TF target gene information.