The term "40S" typically refers to a specific type of ribosomal subunit found in eukaryotic cells. Ribosomes are essential cellular structures responsible for protein synthesis, and the "40S" subunit is the smaller component of the eukaryotic ribosome, which is composed of two subunits: the 40S and the larger 60S subunit. In the context of molecular biology, the 40S subunit plays a crucial role in the initiation of translation, where messenger RNA (mRNA) is decoded to produce proteins. This process is vital for cellular function and growth, as proteins are necessary for various biological activities within organisms.