The Phospho-p107 (Thr369) antibody is a specialized tool used to study the phosphorylation status of the retinoblastoma-like protein p107 at threonine residue 369. p107. a member of the Rb tumor suppressor family (alongside pRb and p130), plays a critical role in cell cycle regulation by binding and inhibiting E2F transcription factors, thereby blocking G1-to-S phase progression. Phosphorylation of p107. particularly at Thr369. is mediated by cyclin-dependent kinases (CDKs) during cell cycle progression. This post-translational modification reduces p107's affinity for E2F, enabling cell cycle entry. The antibody specifically detects this phosphorylation event, serving as a key marker for studying cell cycle dynamics, checkpoint control, and dysregulation in cancer. Researchers employ it in techniques like Western blotting, immunofluorescence, or immunoprecipitation to assess p107 activation status in response to stimuli such as DNA damage, growth signals, or CDK inhibitors. Its applications span cancer research (e.g., analyzing tumor suppressor pathways), developmental biology, and studies of cell differentiation. Validation typically includes testing in phosphorylation-deficient cell models (e.g., Thr369 mutants) or CDK-inhibited conditions to confirm specificity. This reagent is widely used in both basic and translational research to explore the interplay between cell cycle control and disease mechanisms.