Studies have also shown that the addition of ZFL to lung carcinoma and breast carcinoma cell lines could increase the levels of cytoplasmic Ca2+ and the endoplasmic reticulum (ER) stress-related proteins CHOP and ATF4, but the expression of ER stress markers was decreased after 24 h, and inhibition of CTSS failed to cause cell apoptosis (9). Here, CTSS is linked to lung carcinoma.