SUSTech University 1 article published in JoVE Developmental Biology Visualizing Low-Abundance Proteins and Post-Translational Modifications in Living Drosophila Embryos via Fluorescent Antibody Injection Qihong Zheng*1, Xiaoxiang Xiang*1, Yan Yan2,3, Huapeng H. Yu1 1School of Life Sciences, SUSTech University, 2Shenzhen PKU-HKUST Medical Center, 3Division of Life Science, Hong Kong University of Science and Technology This protocol describes the customized antibody-based fluorescence labeling and injection into early Drosophila embryos to enable live imaging of low-abundance proteins or post-translational modifications that are challenging to detect using traditional GFP/mCherry-tag approaches.