Receptor purification

[Mitf]

Suppose we have a cell line that differentiates into pigment cells when treated with a growth factor. Suppose we have an antibody that when we treat the cells with melanogenesis stops...but we know the antibody doesn't recognize the growth factor. we also have GST tagged growth factor... How can we purify the receptor and see if it is receptor tyrosine kinase> Moreover how can we show that the receptor is activated when growth hormone is added?
I was thinking of injecting anti-Ras antibodies into these cells to see if it blocks cell proliferation. And then injecting of a constitutively active mutant Ras protein (i.e., RasD), which hydrolyzes GTP very inefficiently and thus persists in the active state, to see if the cells proliferate in the absence of growth factor. However, I am confused....I don't know if this makes any sense....I would appreciate your help.
THanks