DUSP21 and cancer: We referred to the somatic mutated residues that were equivalent to S93 and N128 in different N-loop-containing PTPs in the cancer databases and found several reports, including S285L in DUSP4, S298G in DUSP6, S249F in DUSP16, S155F in DUSP19, S111N in DUSP21, N297S in DUSP2, N125D in DUSP15, N160D in STYX, N168K in DUPD1, and N453K in SSH3 (Table S1) [15,16].