Berberine chloride inhibits colony formations of National Cancer Institute (NCI)‐H460, A549 and NCI‐H1299 NSCLC cells; induces formation of H2AX phosphorylation at Phospho‐Histone H2A.X (Ser139) (known marker for DNA damage) in NCI‐H460 and A549 cells → results in cell apoptosis. Here, H2AX is linked to non-small cell lung carcinoma.