(c) IBs for HA (top) and GFP (bottom) of total lysates (Input) and GFP immunoprecipitates (IP) from the cell lysates of SY5Y cells co-transfected with the indicated HA-ubiquitin constructs and GFP-p38 or -ANK1-p38 WT or mutant K385R in the presence of lactacystin. (d) Quantification of the levels of each p38 protein ubiquitinated via K63 compared with K48 ubiquitination. Values were corrected by levels of GFP immunoprecipitated. 