PDCD4 and tongue cancer: A newly published work by Zargar et al. [58] linked miR-155 to Pdcd4 (programmed cell death 4) and AP-1 in a net positive feedback loop whose different outcomes can lead either to tongue cancer progression (miR-155 overexpression) or to apoptosis and regression of tumour size (miR-155 knockdown); see Figure 1f.