Supporting Information. Mechanically robust photodegradable gelatin hydrogels for 3D cell culture and in situ mechanical modification Sam C. P. Norris, Stephanie M. Delgado and Andrea M. Kasko * Department of Bioengineering, University of California Los Angeles, 410 Westwood Plaza, 5121 Engineering V, Los Angeles, CA 90095, USA *Corresponding author Email: akasko@ucla.edu Electronic Supplementary Material (ESI) for Polymer Chemistry. This journal is © The Royal Society of Chemistry 2019