MYC and neoplasm: Similarly, as Hsp90 inhibition downregulates c-Myc expression and upregulates the expression of tumour repressor proteins such as p53 and pRB, which inhibits the G1/S transition (Yamaki et al., 2011), expression levels of cell cycle regulatory proteins such as pRB, E2F, cyclin–cyclin-dependent kinase (CDK) complexes could inform predictive biomarkers in specific tumour contexts.