The term "initiator," when used in the field of carcinogenesis, refers to a chemical or physical
Further, there were other chemicals, known as promoters, that if subsequently applied to the same area of the skin could lessen the time needed for the tumor to appear or decrease the dose of the initiator that was needed. Modern molecular biology has expanded the knowledge of carcinogenesis into recognition of the multiple steps that under-lie most human cancers, including mutations in the systems that control cell growth—so-called oncogenes and repressor genes. However, the basic concept remains that certain chemicals are capable of initiating the cancer-causing process.
BERNARD D. GOLDSTEIN
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