MKI67 and cancer: In a related study, A549 spheroid cell cultures were used to construct a lung carcinoma CoC model for the evaluation of the selective cytotoxicity of a tryptophan‐rich peptide P1 against lung cancer.[93] While the overexpression of the Ki‐67 biomarker was utilized to study tumor progression, it can also potentially be used as a potential target for the development of targeted cancer therapies, and their lung CoC can be used to test such targeting efficacy.[278]