Why is there a white spot in my western blot?

1. It may be that the gel is damaged during film transfer, and the signal loss at the gel damage causes white spots to appear in this part of the film.  

2. It may be that there are bubbles between the PVDF film and the gel, pay attention to the use of glass rods to drive away the bubbles between the film and the gel after placing the gel, and then cover the top thick filter paper for transfer.  

3. The antibody solution is small in volume and cannot completely cover the entire membrane, or the container is placed skewed during antibody incubation, resulting in part of the membrane not contacting the antibody, so that no signal is displayed.