Recent studies have indicated that female cancer patients have an increased infection risk and develop more severe forms of COVID-19, and overexpression of CTSL pivotal for COVID-19 infection is a marker of invasion and metastasis in ovarian cancer (Sui et al., 2016; Liang et al., 2020; Rugge et al., 2020; Montopoli et al., 2021). Here, CTSL is linked to cancer.