PCNA and lung carcinoma: At the molecular level, SCFAs derived from the microbiome inhibit the growth of various cancers, such as colon and lung cancer, by modulating GPCRs, histone hyperacetylation, or through the dysregulation of the expression of BCL-2 and PCNA (Zhao et al., 2018; Kim et al., 2019; Mirzaei et al., 2021).