4.3. Experimental methods (1) Cell culture A549 cells were cultured in DME / F-1 culture medium containing 10% fetal bovine serum (93T cell culture ⅱ in DMEM high-sugar culture medium containing 10% fetal bovine serum). The culture was allowed to stand in a constant temperature incubator with a volume fraction of 5%, CO37 ° C, and saturated humidity. Pay attention to observe the growth of the cells. When the cells reached 80% or more of the bottom of the petri dish, take cells with active growth in logarithmic growth.