Translationally controlled tumour protein (TCTP), also known as fortilin [
1] or TPT1 [
2] is a ubiquitously expressed protein of 21 kDa in mice and 23 kDa in humans, expressed in all eukaryotes. It bears no sequence similarity with any other known protein [
1]. It is encoded by a gene that maps to chromosome 13q14.13 [
1,
3] and its expression is highly regulated at transcriptional and translational level and by a wide range of extracellular signals. Its name originates from the observation that TCTP transcripts accumulate in resting cells and are rapidly translated into the protein when the cells require it [
4]. Although TCTP was first considered a tumour protein [
5], its expression is not limited to cancer, as it has been found in normal cells and tissues [
6]. Since its discovery by Yenofsky [
7], it has become clear that TCTP is a multifaceted protein, implicated in many biological processes and exerting biological activity at extracellular and intracellular level [
4]. TCTP participates in cell growth, cell cycle progression, division and proliferation [
8]. An anti-apoptotic function of TCTP in human cancer cells has also been identified. This function may be related to calcium binding [
9‐
12] and inhibition of Bax dimerization [
4]. The interaction between TCTP and p53 prevents apoptosis by destabilizing p53 [
13]. TCTP is also considered a heat shock protein with chaperone-like activity [
14]. It functions as an IgE-dependent histamine releasing factor, having cytokine-like activity in acute allergic response and being involved in immunological response [
15]. Association with a cytoskeletal component, F-actin, and a role in cell shape regulation were also recently discovered [
16], as well as its capacity to bind tubulin and serve as a substrate for Polo-like kinase 1 (Plk-1) [
4].
Ocular vision depends on corneal transparency and shape. These properties depend on the balance between cell proliferation and apoptosis, both mechanisms regulated by TCTP [
17]. The presence and distribution of TCTP in the human cornea has not yet been fully analysed. Studies in the literature have used proteomic techniques and been limited to cultured keratocytes [
18]. Here we evaluated the presence and distribution of TCTP in healthy human corneas for the first time by immunoblotting, reverse transcriptase analysis and immunohistochemistry. Since recent studies suggest that apoptosis [
19], calcium levels [
20] and immunological mechanisms [
21] play a role in the pathogenesis of herpetic stromal keratitis (HSK), we studied TCTP expression in this disease.