Notably, the proportion of CD44+CD62L- EMT cells was markedly greater in CPIP@EV–CM + US treated group (11.1%) than PBS treated group (3.1%) (Fig. 7l, m; Supplementary Fig. 34c), indicating that CPIP@EV–CM + US could produce a strong immune memory effect and prevent tumor metastasis and recurrence in mice. Here, CD44 is linked to neoplasm.