What physical processes regulate star formation in dense environments? Understanding why galaxy evolution is environment dependent is one of the key questions of current astrophysics. I will present the first characterization of the spatial distribution of star formation on a kpc scale in cluster galaxies at z~0.5, and compare it to a field control sample, in order to quantify the role of different physical processes that are believed to be responsible for shutting down star formation. The analysis makes use of data from the Grism Lens-Amplified Survey from Space (GLASS), a large HST cycle-21 program targeting 10 massive galaxy clusters with extensive HST imaging from CLASH and the Frontier Field Initiative. I will also discuss some recent results from GASP (GAs Stripping Phenomena in galaxies with MUSE), a new integral-field spectroscopic survey with MUSE at the VLT aiming at studying gas removal processes in galaxies in the local universe. I will show some examples of galaxies undergoing strong gas stripping and how the project will shed light on where, why and how gas gets removed from galaxies, helping in understanding galaxy quenching and evolution in general.