LCK and cancer: The description of motifs controlling the speed of tyrosine phosphorylation in the LAT adaptor, the modification of which increases the antigenic sensitivity of the TCR, together with a better understanding of the interactions of Lck, ZAP70 and LAT, helps us to better understand relevant biological processes, and broadens the range of new therapeutic approaches for the treatment of immune-based diseases, or the design of CAR-T cells for the treatment of cancer.