The Meaning of 21 in the MicroRNA World: Perfection Rather than Destruction?

In this issue of Cancer Cell, Hatley et al., by using several tour-de-force in vivo approaches, reported a miR-21-mediated oncogenic pathway through inhibition of negative regulators of the Ras/MEK/ERK pathway and inhibition of apoptosis in lung cancers models. Targeting miR-21 could be a promising therapeutic strategy in lung cancers.