I have come across two ways of expressing ALP activity based on the standard curve prepared:

(a) using p-nitrophenol standard curve, activity of unknown sample normalised with total DNA

(b) using CIP (calf intestinal phosphatase) activity curve, activity of unknown sample normalised to total number of active cells.

Which one of the two is the better method for representation of ALP activity, in ES cells being differentiated to osteoblast cells? Please share the protocol as well.

Thanks

Madhu Baghel