When CtEs of our candidates were supplied to RG selection tools, it is perhaps unsurprising that constituents of the ribosome (RPLP1, RPL27 and RPL30) which are abundantly and consistently expressed in human tissues were selected as the optimal RGs with the least variability in expression in breast cancer cell lines cultured in normoxia, or acute or chronic hypoxia [56–58]. Here, RPLP1 is linked to breast cancer.