ALK and lung adenocarcinoma: In order to define the optimum primary antibody incubation time for ALK, serial sections of lung adenocarcinomas were incubated with anti-human ALK antibody clone 5A4 for 2, 4, 8, 16, or 32 min (Fig. 2a, lower panels), while the incubation time of the secondary antibody was kept constant at 8 min.