ESX1 and seminoma: Here, we present studies of the ESX1 gene using the CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) activation system in the testicular seminoma cell line TCam-2 as the first step to investigate its potential function regarding gene cluster regulated by ESX1. In this study we also shown that the previously identified variants lead to amino acid sequence changes in the proline-rich repeat region (PRR) of the ESX1 protein which may affect the correct folding of the protein.