We further examined these function-related genes by RT-PCR, and we found that the relative expression of the DDIT4 was the lowest in the rapamycin + etoposide group compared to rapamycin or etoposide alone (Supplementary Fig. 6d), which was consistent with tumor volumes of four groups in a xenograft model (Fig. 7h). Here, DDIT4 is linked to neoplasm.