ALDH1A1 and cervical carcinoma: CD44 and ALDH1A1 are both considered to be typical CSC surface markers that can be used alone or in combination with other markers to isolate or enrich CSCs in a variety of tumor types including cervical cancer (Liu et al., 2016; Wang et al., 2018; Tomita et al., 2016; Tulake et al., 2018).