There are three steps involved in tumour development/transformation: initiation, promotion and progression. For each of these three steps state if the effect is permanent or not, indicating why in each case.
Answer:
Initiation is the first step in tumor development it involves the irreversible changes in DNA sequences. This is irreversible due to the fact that these changes are 'hereditary' and are passed onto daughter cells during replication.
Promotion is the second stage of tumor development. In this stage growth stimuli induce the altered DNA to proliferate and grow. Since these stimuli do not cause change do DNA, but alter gene expression, these effects are reversible.
Progression is the final step of tumor development. This is the conversion of a benign tumor to a malignant tumor. This is due to genetic instability. This is an irreversible change due to the genetic and epigenetic changes that occured.