Please tell me the storage method of HL-60 cell line!

[unknown at dl.ac.uk]

Hi, everybody
 I stored HL-60 cells in liquid nitrogen according to standard method. But
cells had poor viability when I recoverd cells from liquid nitrogen and
cultured one day.
  How can I store HL-60 cell line to get good viability? Please tell me the
method!



  Yoshiyuki Shibata
  Department Oral Radiology, Nagasaki University