Streaks and vertical lines in two-dimensional electrophoresis can result from sample contamination, protein aggregation, improper IEF conditions, inadequate gel quality, or trapped air bubbles. Addressing these issues through careful sample preparation and optimal conditions is essential for clearer results.

Dear, I hope you are doing well! Vertical streaks in 2DE electrophoresis are generally associated with excess salts in the samples. They can also result from issues during isoelectric focusing. In your specific case, I believe combining both factors is causing the vertical streaks. I suspect the first separation (isoelectric point) did not occur properly.