In addition, tumor suppressors miR-1285, miR-608, miR-506, miR-30a-5p and miR-146a-5p have been demonstrated to impair GEM resistance of PC by silencing expression of YAP1/EGFR/β-catenin, ribonucleotide reductase M1 (RRM1)/CDA, sphingosine kinase 1 (SPHK1)/Akt/NF-κB, FOXD1/ERK and the tumor necrosis factor receptor-associated factor 6 (TRAF6)/NF-kB p65/P-gp signaling, respectively (Li et al., 2016; Huang et al., 2017; Rajabpour et al., 2017; Zhou et al., 2019; Meng et al., 2020). Here, SPHK1 is linked to pachyonychia congenita.