The mRNA transcripts of the CDKN1A gene carry the genetic information necessary for the synthesis of the p21 protein. This mRNA is transcribed from the DNA of the CDKN1A gene and then goes through a process of translation to produce the p21 protein. The p21 protein, in turn, interacts with CDKs to regulate the progression of the cell cycle. Dysregulation of the CDKN1A gene and its protein product p21 can have significant implications for cell cycle control and the development of diseases like cancer.