tokens: In addition , other sigma - 1 receptor agonists - PPBP ( 0 . 1 , 1 . 0 , or 10 micro M ) [ 22 ] - [ 26 ] and DHEA - sulphate ( 0 . 1 , 1 . 0 , or 10 micro M ) [ 9 ] , [ 27 ] , [ 28 ] - significantly increased the number of such cells , also in a concentration - dependent manner ( Figure 3 ) .