IL6 and neoplasm: When control shRFP-expressing MSFs were induced to senesce, they stained positive for SA-βgal, expressed increased levels of IL-6, (Fig. 8a–e) and upon co-injection with PDSC5 tumour cells, promoted tumour cell growth 3.2-fold compared with non-senescent, shRFP-expressing MSFs (Fig. 8f).