Proteins perform most of the cell's functions, and each protein must be present in a certain amount to make the cell work correctly. One way to control the number of proteins produced consists of controlling the number of mRNA molecules produced during transcription. The gene sequence includes what will be transcribed to RNA and the information that says how much of a gene product has to be produced. This part of the sequence is called a regulatory sequence. Understanding how this sequence works could lead to better predictions of mRNA expression. In 2020, Agarwal and Shendure developed the Xpresso model in which they predicted the amount of mRNA from the DNA sequence of the promoter region of a protein-coding gene.