ASPG and osteonecrosis: Consistent with the pharmacokinetic experiment, we observed an association between plasma dexamethasone concentration and asparaginase activity (P = 0.005; S1 Fig) at the end of 6 weeks in the osteonecrosis experiment, In the 27 mice that received both dexamethasone and asparaginase, there was a significant trend towards higher dexamethasone levels (P = 0.027; Fig 4A) and higher asparaginase activity (P = 0.036; Fig 4B) in osteonecrosis-positive cases.