Hello Tanvi,

Usually, a vertical streaking could be caused because of poor sample preparation as incomplete protein solubility could block the protein from entering the gel. Make sure that there is adequate homogenization of the lysate and centrifuge the lysate to get rid of any particulate matter that may cause interference. There should be no aggregates in the sample when loading.

Another possibility could be sample degradation. So, ensure that you add protease and phosphatase inhibitors during lysate preparation. As far as possible avoid repeated freeze-thaw cycles of the sample.

Finally, too much protein loading could be the cause. Accordingly, you may decrease the amount of protein loading per well.

Best.