However, although numerous models of apoptosis have been described in tumour cells (e.g., calcium-binding proteins, protein kinases, nuclear transcription factors, oncogenes and cysteine proteases) (Rowan and Fisher, 1997; Favrot et al, 1998), the pathway by which the gef gene acts in MCF-7 cells presently remains under investigation. Here, CTSB is linked to neoplasm.