Platelet-specific deletion of SHARPIN curtails Met-1 ubiquitination and reduces NF-κB pathway signaling. Western blots of SHARPIN^fl/fl Pf4-Cre or SHARPIN^fl/fl GPIbα-Cre mouse platelets following stimulation with an agonist cocktail of 400 μM of PAR4 agonist peptide, 50 μM of ADP, and 50 μM of epinephrine, lysed at the indicated times, subjected to SDS-PAGE, and blotted for Met-1 ubiquitin (n = 3) (A) and phosphoserine 536 (B) of the p65 (RelA) subunit of NF-κB. (C) Summary of signal intensity of pS536 NF-κB (n = 5; *P < .05). β-actin re-probes were used as loading controls. (D) Western blot of OTULIN indicating similar levels in SHARPIN^fl/fl GPIbα-Cre⁻ and SHARPIN^fl/fl GPIbα-Cre⁺platelet lysate (n = 3).