Of interest, Zeng et al. demonstrated increase in autophagy in breast cancer cell line models (MCF-7, LCC6) sequentially exposed to doxorubicin and IGF-1R/IR tyrosine kinase inhibitor; however, autophagy in these experiments could have been activated by doxorubicin rather than IGF1-R inhibition.[38]. This evidence concerns the gene IGF1R and breast cancer.