We discussed in class how adding an activated ras oncogene to cells growing in culture was sufficient to turn these cells cancerous. We agreed that this was only possible because these cells had already acquired some of the mutations necessary to become cancerous before the ras gene was added. Were these early mutations likely to be activation of oncogenes or inactivation of tumor suppressor genes? Explain.
a) Activation of oncogenes.
b) Inactivation of tumor suppressor genes.
c) Activation of tumor suppressor genes.
d) Inactivation of oncogenes.