Glycosylation is the most abundant and diverse form of protein post-translational modification, but our knowledge of the roles of specific glycans on specific proteins is limited. Joshi, Clausen and colleagues discuss different approaches to study this modification, and review our current understanding of glycosylation pathways and the biological functions of protein glycolsylation.

In this issue, Gao and colleagues highlight the most recent breakthroughs in CRISPR–Cas-related plant biotechnologies and discuss important current and future applications — in plant breeding and accelerated domestication; in increasing plant yield and quality; and in disease and herbicide resistance.

This month Nature Reviews Molecular Cell Biology turns 20! To mark the anniversary, we present a Collection of Reviews and Journal Clubs that highlight advances in 10 selected research areas covered by the journal. We also introduce a Series of short World View articles that turns the spotlight on the new generation of group leaders.

RNA tailing is the addition of non-templated nucleotides to the 3′ end of RNA. To learn about non-canonical RNA tails and how human terminal nucleotidyltransferases modify RNAs post-transcriptionally to control RNA stability and activity, read the Review by Yu & Kim.

G-quadruplex structures in DNA and RNA are linked with gene regulation and genome instability, and could serve as therapeutic targets in cancer. To learn about their diverse functions, read the Review by Balasubramanian and colleagues.

As billions of cells die during mammalian embryogenesis and daily in adult organisms, it is essential to clear dead cells and cellular debris for tissue homeostasis, tissue repair and organismal health. Read the Review by Green, Heckmann and colleagues to learn about efferocytosis, the phagocytosis of dead and dying cells.

Epithelial–mesenchymal transition (EMT) is the process by which epithelial cells gradually lose epithelial characteristics and acquire features of mesenchymal cells, including the ability to migrate. EMT occurs during normal animal development and cancer cell invasion. To better characterize EMT and to help with the reporting of data and results from different experimental models and settings, Yang et al. provide Guidelines and definitions for research on epithelial–mesenchymal transition.

Oxygen is essential for most species, as it sustains intracellular bioenergetics and is consumed by many biochemical reactions. But cells can adapt to low oxygen levels (hypoxia) by activating mechanisms that coordinate diverse biological outputs. To learn more about how cells sense and adapt to hypoxia, see Lee, Chandel & Simon.

The perturbation of cholesterol balance can lead to cardiovascular disease, as well as neurodegeneration and cancer. To learn more on cholesterol metabolism and the maintenance of cholesterol homeostasis, see Song and colleagues.

Mammalian long non-coding RNA (lncRNA) species are degraded by the RNA surveillance machinery. This regulated degradation is vital for genome integrity, stem cell pluripotency and immune cell activation. To learn more on lncRNA surveillance in physiology and human disease, see Basu and colleagues.

Beyond recycling cellular waste, lysosomes mediate the adaptation of cell metabolism to environmental changes ― they are a platform for intracellular signalling and communication. To learn more about their cellulalr functions, and roles in physiology and disease, see Ballabio and Bonifacino.

Intracellular organelles can communicate and integrate their activities by forming close contacts, known as ‘membrane contact sites’ (MCSs). Research on MCSs is starting to reveal their many diverse biological functions. See Prinz and colleagues.