{'fraction_non_alphanumeric': 0.020029673590504452, 'fraction_numerical': 0.0051928783382789315, 'mean_word_length': 5.778894472361809, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Chemical Inhibitors when Timing Is Critical: A Pharmacological Concept for the Maturation of T Cell Contacts

Cellular signal transduction proceeds through a complex network of molecular interactions and enzymatic activities. The timing of these molecular events is critical for the propagation of a signal and the generation of a specific cellular response. To define the timing of signalling events, we introduce the combination of high‐resolution confocal microscopy with the application of small‐molecule inhibitors at various stages of signal transduction in T cells. Inhibitors of Src‐family tyrosine kinases and actin dynamics were employed to dissect the role of the lymphocyte‐specific tyrosine kinase Lck in the formation and maintenance of T cell receptor/CD3‐dependent contacts. Anti‐CD3ε‐coated coverslips served as a highly defined stimulus. The kinetics of the recruitment of the yellow fluorescent protein‐tagged signalling protein ZAP‐70 were detected by high‐resolution confocal microscopy. The analysis revealed that at 5 min after receptor engagement, Lck activity was required for maintenance of contacts. In contrast, after 20 min of receptor engagement, the contacts were Lck‐independent. The relevance of the timing of inhibitor application provides a pharmacological concept for the maturation of T cell–substrate contacts.