Autophagic hTERT-BJ1 fibroblasts, generated by over-expression of autophagy promoters, such as cathepsin B, and senescent hTERT-BJ1 fibroblasts, generated via over-expression of CDK inhibitors, such as p21, are able to enhance tumour growth and metastasis when co-injected with breast cancer cells in vivo [34, 35]. Here, CTSB is linked to breast carcinoma.